A 3D EPG does seem rather a trivial thing to be putting time and effort into but I guess they have to showcase the 3D features and people with a 3D TV and a 3D capable box, especially a paid-for-up-front TiVo, will want to have something 'cool' to watch on them, even if the 3D programming is in short supply.
Any day now, you won't need the remote any more, you'll be able to put your hand out towards the projected 3D EPG and manipulate it without having to wipe the finger-lickin' Colonel's secret recipe from your hands first.