PSX/PS2/PS3 cleanly from HD in a very attrative gui with active development crew.
XBMC or equivalent/Boxxee.
N64,DC,Saturn emulators that run pretty dang good.
Multiplayer network, either on Sony's or off, but something for us home brewers that are banished,etc or not. Let Sony simply ban cheaters and not homebrewers....that would be ideal.
Training system.
What more could you hope for, really.
Slick CFW system which would allow 100% brick block, such as emulated nand.
Gamecube emulation at 100%.
And most important of all, a steady steady stream of exploits from 3.41 to infinity and every one in between.