It's almost impossible to keep up with Google changes much less understand their real impact as they relate to your website.  SEOMoz has a great section of their website entitled "Google Algorithm Change History". The following is straight from SEOMoz with links to the top 50 recent Google changes.  The first is rather exhaustive and the second provides an attempt at practical applicatioin.  More to come...

March 50-Pack - April 3, 2012

Google posted another batch of update highlights, covering 50 changes in March. These included confirmation of Panda 3.4, changes to anchor-text "scoring", updates to image search, and changes to how queries with local intent are interpreted.

Search quality highlights: 50 changes for March (Google)  The following list is explained in this article (funny thing... there only seem to be 44).

  1. Autocomplete with math symbols.
  2. Improvements to handling of symbols for indexing.
  3. Better scoring of news groupings.
  4. Sitelinks data refresh.
  5. Improvements to autocomplete backends, coverage.
  6. Better handling of password changes.
  7. Better indexing of profile pages.
  8. UI refresh for News Universal.
  9. Improvements to results for navigational queries.
  10. High-quality sites algorithm data update and freshness improvements.
  11. Live results for UEFA Champions League and KHL.
  12. Tennis search feature.
  13. More relevant image search results.
  14. Fresher image predictions in all languages.
  15. SafeSearch algorithm tuning.
  16. Tweaks to handling of anchor text.
  17. Simplification to Images Universal codebase.
  18. Better application ranking and UI on mobile.
  19. Improvements to freshness in Video Universal.
  20. Fewer undesired synonyms.
  21. Better handling of queries with both navigational and local intent.
  22. Improvements to freshness.
  23. Improvements to processing for detection of site quality.
  24. Better interpretation and use of anchor text.
  25. Better local results and sources in Google News.
  26. Deprecating signal related to ranking in a news cluster.
  27. Fewer “sibling” synonyms.
  28. Better synonym accuracy and performance.
  29. Retrieval system tuning.
  30. Less aggressive synonyms.
  31. Update to systems relying on geographic data.
  32. Improvements to name detection.
  33. Updates to personalization signals.
  34. Improvements to Image Search relevance.
  35. Remove deprecated signal from site relevance signals.
  36. More precise detection of old pages.
  37. Tweaks to language detection in autocomplete.
  38. Improvements in date detection for blog/forum pages.
  39. More predictions in autocomplete by live rewriting of query prefixes.
  40. Expanded sitelinks on mobile.
  41. More accurate short answers.
  42. Migration of video advanced search backends.
  43. +1 button in search for more countries and domains.
  44. Local result UI refresh on tablet.

Google’s March Updates: Anchor Text, Image Search, Navigational Search & More (SEL)