WordPress 3.1 RC3  has been release.
In summary, RC3 has removed the AJAX list tables implemented in RC2 because of bugs and usability issues.
Here is the blog post from WordPress.org:
WordPress 3.1 Release Candidate 3 is now available. After careful evaluation of the 3.1 features in RC2, we recognized the need to make some adjustments. There are some significant differences from previous versions of 3.1, so please review the changes if you have been developing against a beta or RC version.
The biggest change is the removal of AJAX list tables, which had been an effort to move all of our list-style screens to full AJAX for pagination, searches, and column sorts, and to consolidate the list-style screens into a single API that plugins could leverage. Unfortunately, with more testing came realizations that there were too many major bugs and usability issues with how the functionality was implemented, so we’ve spent the last week rolling back the most important portions of the feature.
- For users: AJAX has been entirely disabled for the list tables. We hope to bring this back again, in a form that is properly and fully implemented, in a future release. Column sorting remains, but everything else has returned to its 3.0 state.
- For developers: The entire list table API is now marked private. If you attempt to leverage new components of the API, you are pretty much guaranteeing that your plugins will break in a future release, so please don’t do that. We hope to enable all the fun new goodies for public use in a future release.
This is the only way we could prevent any regressions in functionality and usability from WordPress 3.0 to 3.1. That’s right, users and plugin authors can still do everything you used to be able to do (and a little bit more).
Because of the code churn between RC2 and RC3, this release candidate needs a lot of testing. Every list screen needs testing. In particular, the comment moderation screen needs testing, especially with keyboard shortcuts (if you didn’t know about those, now’s your chance to try them out).
Other fixes in RC3 include:
- Properly display the author dropdown in Quick Edit
- Various important fixes to numerous taxonomy query variables
- Fixes to the theme deletion process
- Fixes to pages used for posts
- IIS and Multisite: Avoid resetting web.config on permalink save
- Properly validate post formats and their rewrite rules
I’m assembling a group of friends in Washington, D.C., this weekend to test WordPress 3.1 and provide feedback. We’d love to see this idea catch on among friends at coffee shops around the world. (We’ll blog our results, and we’re thinking about using the hashtag #wptest on Twitter.) If you are testing the release candidate and think you’ve found a bug, there are a few ways to let us know:
- Post it to the Alpha/Beta area in the support forums 
- Report it to the wp-testers mailing list 
- Join the development IRC channel and tell us live at irc.freenode.net #wordpress-dev
- File a bug ticket on the WordPress Trac 
We’re going to study this release carefully to see where we can improve on our internal processes in the future. With that, our requisite haiku, authored by Jane:
Pulling the AJAX –
sometimes you need to step back
and show some restraint.
Download: WordPress 3.1 RC 3