The rumors were right. PS3 firmware 2.1 is released. Features:

• Blu-Ray 1.1 Support. This supports Picture-in-Picture and other enhancements
• Support for DivX and VC-1 WMV movies.
• Voice changer

From the comments:

(Sporty) Videos now properly show thumbnails.
(alisound) Xvid/.avi works. Older .wmv files don’t.