It may be nothing, but have you seen the list of games to be shown next month at E3?
Here it is:

Sony Computer Entertainment:
Killzone 2 (PS3)
LittleBigPlanet (PS3)
MotorStorm: Pacific Rift (PS3)
PixelJunk Eden (PS3)
Resistance 2 (PS3)
SIREN: Blood Curse Episode #1 [PSN] (PS3)
SOCOM: Confrontation (PS3)

(source: http://www.game-focus.com/?nav=new&nid=8512 )

No Wipe...
Well, IMO, either it will be out before E3, either Sony doesn't want to show a finished game as they would have to explain why it's not available yet.
What do you guys think 'bout it?

PS: MGS4 is a great game