Google Algorithm Change History - Part 2

Panda #24 — January 22, 2013

Google announced its first official update of 2013, claiming 1.2% of queries affected. This did not seem related to talk of an update around 1/17-18 (which Google did not confirm).
Google Announces 24th Panda Refresh; Not Related To January 17th (SER)
Google Panda Update Version #24; 1.2% Of Search Queries Impacted (SEL)

Panda #23 — December 21, 2012

Right before the Christmas holiday, Google rolled out another Panda update. They officially called it a "refresh", impacting 1.3% of English queries. This was a slightly higher impact than Pandas #21 and #22.
Confirmed: A Panda Refresh, Version #23 (SER)

Knowledge Graph Expansion — December 4, 2012

Google added Knowledge Graph functionality to non-English queries, including Spanish, French, German, Portuguese, Japanese, Russian, and Italian. This update was "more than just translation" and added enhanced KG capabilities.
Get smarter answers from the Knowledge Graph from Português to Japanese to Russian (Google)
Google’s Knowledge Graph Expands To More Languages, Including Italian, French, Japanese And Russian (TechCrunch)

Panda #22 — November 21, 2012

After some mixed signals, Google confirmed the 22nd Panda update, which appears to have been data-only. This came on the heels of a larger, but unnamed update around November 19th.
Official Google Panda #22 Update: November 21 (SER)
Confirmed: Google Panda Refresh #22 On November 21st; 0.8% Of Queries Impacted (SEL)

Panda #21 — November 5, 2012

Google rolled out their 21st Panda update, roughly 5-1/2 weeks after Panda #20. This update was reported to be smaller, officially impacting 1.1% of English queries.
Google Releases Panda Update 21, Impacts 1.1% Of US Queries In English (SEL)
Official: Google Panda Refresh On November 5th (Version 21) (SER)

Page Layout #2 — October 9, 2012

Google announced an update to its original page layout algorithm change back in January, which targeted pages with too many ads above the fold. It's unclear whether this was an algorithm change or a Panda-style data refresh.
It’s “Top Heavy 2″ As Google Rolls Out Update To Its Page Layout Algorithm (SEL)
Google Page Layout Algorithm Officially Updated (SER)

Penguin #3 — October 5, 2012

After suggesting the next Penguin update would be major, Google released a minor Penguin data update, impacting "0.3% of queries". Penguin update numbering was rebooted, similar to Panda - this was the 3rd Penguin release.
Google Penguin Update 3 Released, Impacts 0.3% Of English-Language Queries (SEL)
Google Released 3rd Penguin Update: Not Jarring Or Jolting (SER)

August/September 65-Pack — October 4, 2012

Google published their monthly (bi-monthly?) list of search highlights. The 65 updates for August and September included 7-result SERPs, Knowledge Graph expansion, updates to how "page quality" is calculated, and changes to how local results are determined.
Search quality highlights: 65 changes for August and September (Google)

Exact-Match Domain (EMD) Update — September 27, 2012

Google announced a change in the way it was handling exact-match domains (EMDs). This led to large-scale devaluation, reducing the presence of EMDs in the MozCast data set by over 10%. Official word is that this change impacted 0.6% of queries (by volume).
Google's EMD Algo Update - Early Data (SEOmoz)
The EMD Update: Google Issues “Weather Report” Of Crack Down On Low Quality Exact Match Domains (SEL)

Panda #20 — September 27, 2012

Overlapping the EMD update, a fairly major Panda update (algo + data) rolled out, officially affecting 2.4% of queries. As the 3.X series was getting odd, industry sources opted to start naming Panda updates in order (this was the 20th).
20th Google Panda Algorithm Update: Fairly Major (SER)
How Do You Know If Google Panda Or EMD Hurt Your Site? (SER)

Panda 3.9.2 (#19) — September 18, 2012

Google rolled out another Panda refresh, which appears to have been data-only. Ranking flux was moderate but not on par with a large-scale algorithm update.
Google Rolls Out Panda 3.9.2 Refresh (SER)
Panda Update 3.92 Rolling Out (Or Is It Panda 20 Time?) (SEL) 

Panda 3.9.1 (#18) — August 20, 2012

Google rolled out yet another Panda data update, but the impact seemed to be fairly small. Since the Panda 3.0 series ran out of numbers at 3.9, the new update was dubbed 3.9.1.
Confirmed: Google Panda 3.9.1 Update (SER)
Google Panda Refresh On August 19th: Version 3.9.1 (SEL)

7-Result SERPs — August 14, 2012

Google made a significant change to the Top 10, limiting it to 7 results for many queries. Our research showed that this change rolled out over a couple of days, finally impacting about 18% of the keywords we tracked.
SERP Crowding & Shrinkage: It's Not Your Imagination (SEOmoz)
7 Is The New 10? Google Showing Fewer Results & More From Same Domain (SEL)

DMCA Penalty — August 10, 2012

Google announced that they would start penalizing sites with repeat copyright violations, probably via DMCA takedown requests. Timing was stated as "starting next week" (8/13?).
An update to our search algorithms (Google)
The Emanuel Update: Google Will Penalize Sites Repeatedly Accused Of Copyright Infringement (SEL)

June/July 86-Pack — August 10, 2012

After a summer hiatus, the June and July Search Quality Highlights were rolled out in one mega-post. Major updates included Panda data and algorithm refreshes, an improved rank-ordering function (?), a ranking boost for "trusted sources", and changes to site clustering.
Search quality highlights: 86 changes for June and July (Google)
Google’s June-July Updates: Site Clustering, Sitelinks Changes & Focus On Page Quality (SEL) 

Panda 3.9 (#17) — July 24, 2012

A month after Panda 3.8, Google rolled out a new Panda update. Rankings fluctuated for 5-6 days, although no single day was high enough to stand out. Google claimed ~1% of queries were impacted.
Official: Google Panda 3.9 Refresh (SER)

Link Warnings — July 19, 2012

In a repeat of March/April, Google sent out a large number of unnatural link warnings via Google Webmaster Tools. In a complete turn-around, they then announced that these new warnings may not actually represent a serious problem.
Insanity: Google Sends New Link Warnings, Then Says You Can Ignore Them (SEL)
Google Sends Out New Batch Of Unnatural Link Notifications (SER)

Panda 3.8 (#16) — June 25, 2012

Google rolled out another Panda data refresh, but this appeared to be data only (no algorithm changes) and had a much smaller impact than Panda 3.7.
Official Google Panda Update Version 3.8 On June 25th (SEL)
Google Panda 3.8 Live: June 25th & Refresh Only (SER)

Panda 3.7 (#15) — June 8, 2012

Google rolled out yet another Panda data update, claiming that less than 1% of queries were affect. Ranking fluctuation data suggested that the impact was substantially higher than previous Panda updates (3.5, 3.6).
Confirmed: Google Panda 3.7 Update (SER)
The Bigfoot Update (AKA Dr. Pete Goes Crazy) (SEOmoz)

May 39-Pack — June 7, 2012

Google released their monthly Search Highlights, with 39 updates in May. Major changes included Penguin improvements, better link-scheme detection, changes to title/snippet rewriting, and updates to Google News.
Search quality highlights: 39 changes for May (Google)
Google’s May Updates: Inorganic Backlinks, Page Titles, Fresh Results & More (SEL)

Penguin 1.1 (#2) — May 25, 2012

Google rolled out its first targeted data update after the "Penguin" algorithm update. This confirmed that Penguin data was being processed outside of the main search index, much like Panda data.
Google Releases Penguin Update 1.1 (SEL)

Knowledge Graph — May 16, 2012

In a major step toward semantic search, Google started rolling out "Knowledge Graph", a SERP-integrated display providing supplemental object about certain people, places, and things. Expect to see "knowledge panels" appear on more and more SERPs over time. Also, Danny Sullivan's favorite Trek is ST:Voyager?!
Introducing the Knowledge Graph: things, not strings (Google)
Google Launches Knowledge Graph To Provide Answers, Not Just Links (SEL)

April 52-Pack — May 4, 2012

Google published details of 52 updates in April, including changes that were tied to the "Penguin" update. Other highlights included a 15% larger "base" index, improved pagination handling, and a number of updates to sitelinks.
Search quality highlights: 52 changes for April (Google)
Google’s April Updates: Bigger & Tiered Index, Document Ranking, Sitelink Changes & More (SEL)

Panda 3.6 (#14) — April 27, 2012

Barely a week after Panda 3.5, Google rolled out yet another Panda data update. The implications of this update were unclear, and it seemed that the impact was relatively small.
Confirmed: Panda Update 3.6 Happened On April 27th (SEL)