- is_feed() status is preserved when handling 404s #3019 
- manually entering pages greater than the number of pages for a given post now shows the highest numbered page #3039 
- improved security in wp-db-backup plugin 
- user description is no longer HTML-entity converted going into the database #3069 
- fix forrel="nofollow nofollow"
default category is no longer checked by default #2938 (Saving this one for 2.1… won’t be in 2.0.5 final)
- plugins are sorted by plugin name, instead of filename #2412  
- multi-line options in /wp-admin/options.php are preserved #2456 
- the authors dropdown is now sorted by display_name #2370 
- the_meta() properly ignores keys that start with an underscore #2478 
- post meta keys and data are escaped properly on the post screen 
- users are prevented from entering strings that will be interpreted as serialized data when coming out of the database #2591  
- make_clickable() no longer adds links within links #3228  
- error suppression #2331 , #2745 , #1999 , #2759 , #3179 
- i18n fixes #3109 
This is not an exhaustive list… just the important ones, or the ones I thought people would care about.
Testers, check the wp-testers list. There is a release candidate for you to try out.