Currently:
Larger hard drive
Two tuners (record two shows simultaneous while watching a previously recorded show, or watch a live show while a show is recording)
Expanded search (more characters than just a-z and space)
Linux games (however this means no instant weather on 9500)
I think I read in the forum somewhere that it has automatic commercial skip. I'm not certain if this is a new feature, or just refering to the standard 30 second skip also found on the 501.
In the future (maybe):
USB support - who knows what devices this means
Internet browsing