Twenty Eleven, the default theme that still had a lot of bugs in the last beta releases, has been tweaked. They have also added an option for randomised headers. I’ve uploaded the theme to one of my sites and it still feels like it needs some things updated. As it stands, the single.php template does not show any sidebars, which I thought was rather strange.
RC2 appears to be working fine in my test area though I would be reluctant to upload it to a live site as yet, particularly with the stable release just around the corner. If you want to try it out though, you can do so via the link below :)