Hell, you don't want to reveal all your goodies at once! That's the WORST thing Sony could do. It would surely get a big bang in sales--but would die a month later.
It's better to make a big announcement like Resistance 2 & In-game XMB coming very soon every 2 weeks to a month.
The idea is to keep the hype up and get free press coverage and advertising by stringing together multiple announcements over time.
You can't let people go through a long drought with no announcements--it kills your momentum--that is what would happen if they revealed everything.
Same is true of Nintendo & MS.
Well, I now only have access to a PS3 & 360...Plan on buying a wii soon (lol, if I can ever find one available!) but will probably wait until some of the major RPG's come out like Dragon Quest & Tales, etc.
Anyhow, I'm so far behind in games to play that I'm not in a huge hurry (lol, haven't even gotten a chance to finish God of War II yet!)