Realistically, nothing can top MS for shock value. I think once people get over the shock in a few days, they'll realize that MS's conference didn't bring anything new to the table gaming-wise for this year. Therefore, the best thing Sony can do is announce new games that are actually going to be released this Fall in NA. I know it's not Sony's style to release a game so quickly after the first announcement, but this would be the best move. Even if they just announce something like Jak 4 or Uncharted 2, PS fans will be able to boast that they're actually getting something new now instead of getting some game years down the road that some other console had.
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.
