The Infinite Abyss blog has some pretty amazing screenshots and video of a potential new TiVo interface with plenty of details about each. If this is true, it's certainly breaking loads of nondisclosure agreements that testers must abide, if false it's still a pretty interesting and convincing new direction that TiVo could someday take.
I love the preview of each top level menu's options (seems like a time-saver when you're hunting for a specific function) and aside from the standard TiVo screens it looks a lot like the functionality on AppleTV where buying and renting video is first and foremost. I like the idea of owner profiles (mom, dad, kids get different shows/options) and hope that becomes a reality someday. The overall visual design of it reminds me of Windows Media Center and I can't say I like the large images across the top -- they take up 1/3 of the screen without conveying any information. [thanks davezatz for the pointer]