Considering the Kingdom Hearts team is still busy with a game that won't come out till Holiday '09 at the earliest (FF Versus XIII), I think it's safe to say little to no work has been done on Kingdom Hearts 3. I think we'll probably hear something about it at E3.... E3 2009, that is.
I'm betting if we do hear anything about it this year, it'll be in the form of a CG trailer shown only to the press that doesn't reveal anything about the platform it'll be on. That's just how Square Enix seems to operate.
My Top 5:
Shadow of the Colossus, Metal Gear Solid 3, Shenmue, Skies of Arcadia, Chrono Trigger
My 2 nex-gen systems: PS3 
and Wii 
Prediction Aug '08: We see the PSP2 released fall '09. Graphically, it's basically the same as the current system. UMD drive ditched and replaced by 4-8gb on board flash memory. Other upgrades: 2nd analog nub, touchscreen, blutooth, motion sensor. Design: Flip-style or slider. Size: Think Iphone. Cost: $199. Will be profitable on day 1.
