For those of you who really like to be ahead of the curve on WordPress today is your chance. Andrew just announced the release of the Beta 1 version of WordPress 3.5 and it is available for download. Obviously it is not recommended you run it on a production site but for plugin developers, like me, and them designers this is that wonderful window of opportunity for you to make sure everything holds together (and it should) in the new version.
The official launch date is still scheduled for December 5 (why that date?) but the newest theme, 2012, is now available for download in the repository.