WordPress 3.5 Beta 3 has been released!
More than 300 bug fixes since beta 2, Add Media dialog is complete, updated jQuery UI 1.9.1, SimplePie 1.3.1, and TinyMCE 3.5.7.
RC1 should be out next week followed by the final version of WordPress 3.5 which is targeted on 5th December 2012.
Download: WordPress 3.5 Beta 3