Found this interesting article..

Trophies will be coming to the PS3 by June 12th, when Metal Gear Solid 4 finally arrives. This follows reports from several other websites and boards that they are coming to the PS3 XMB very soon. Lets all hope that this Insider has got it right because this new feature will be a great addition to the PS3 system
Yes so all them trophies you've got whilst playing Uncharted, Warhawk, etc will be all nice and shiny in your PSN for 12th June maybe tying in with the release of Metal Gear Solid 4.

Insider: XMB Trophies arriving by June 12th [Exclusive] « Sev1512