I don't think it exists really, but I reckon we can piece things together
2000 - 2003 :- Practically monthly updates, pretty much shooting in the dark to remember what it was the changes as I don't think anybody really understood things as fully nor monitored as closely.
Feb 2003 :- First 'named' update, Boston.
April 2003 :- Cassandra
May 2003 :- Dominic
June 2003 :- Esmerelda
November 2003 :- FLORIDA! Boom, this was the first one that made SEO what it is today. It started ranking sites in a way that nobody could fully work out. It blasted the spammers (although many quality pages were also effected if they were using the same over-optimisation/ stuffing techniques) and started the link race game that we have today.
January 2004 :- Austin. Hammered some more sites in a Florida type fashion. Seemed to introduce the QDF factor.
February 2004 :- Brandy.
February 2005 :- Allegra.
September 2005 :- Something funny happens here
October 2005 : - JAGGER! First step in the fight back against the new link currency. Recipricol links devalued, link farms devalued, paid links (where detected) penalised and/or devalued. Sandbox changes to make it harder to rank for new sites.
October 2005 :- Jagger 2. Domain age seems to play a bigger part of the algorithm.
October 2005 :- Jagger 3. Refinements to the first 2.
December 2005 to March 2006 :- BIG DADDY! Algorithm change to evaluate link trust. Non-thematic links, lots of recipricol links, lots of links on a page, lots of links from low quality sites all
August 2006 :- Lots of little things.
November 2006 :- Lots of minus position penalties for unnatural looking link profiles.
June 2007 :- Buffy. Not a real update apparently but there was one earlier that month which I think added some ridiculous penalties of up to -950!
April 2008 :- Dewey. Massive changes depending on what data centre you went through and changed SERPs multiple time each day. Google may have also given a cheeky little boost to their own intellectual property... Also think it was this one that started to stink up the UK search results with loads of foreign sites (not as xenophobic as it sounds, lol).
August 2008 :- Devalued exact anchor text links?
March 2009 :- VINCE! Also known as the brand update. Google gave a significant boost for sites that had a 'brand' (under the guise of 'trust'). Ultimately this moved the playing field to give the advantage to bigger sites with bigger budgets. Requires SEOs to improve visibility across sites to show that they're not a fly-by-night organisation. [Thanks Gianluca]
January 2010 :- Caffeine. Fresher results, more verticals, real time. Algorithm itself doesn't seem to change much. More of a sys admin change than anything.
May 2010 :- MAY DAY. Smacked some thin affiliates and pages with no content (auto-generated pages without products specifically).
December 2010 :- Started taking into account poor reviews and penalising those merchants. Black hats get to work reviewing their competitors. Perhaps the start of a bigger sentiment change with them also using Facebook and Twitter (though if that were the case I'd expect to never see Virgin Media in the search results :D).
January 2011 :- Content farms that scrape content take a hit. Harbinger of Panda.
March to April 2011 :- PANDA! Hammers (some) content farms.
All right, I'm probably missing lots of big ones, but if other people want to contribute I'm sure we can do something with this