We actually know a lot about Ocelot:(If you haven't played all the games, you might not want to read this) Throughout the entire mythology of the Metal Gear, Ocelot was working for the Patriots. In every game he aligns himself with the "bad guys" but in actuality he's always working as a double agent for the Patriots (the American branch of the Philsophers). We also know that he's the son of The Boss and that he was taken away from her at birth by the Patriots. However, he is not aware of this fact.
What'll be interesting about MGS4 is how the relationship between Liquid and Ocelot plays out considering they have opposite goals in mind (Liquid wants to destroy those who Ocelot works for).
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.
