Listen up, kids: Edge and others report that a leaked document from SEGA strongly suggests that Sony intends to sell all PS2 games as downloads for the PS3 on the Playstation Network. Why SEGA? Well, the document suggested that Sony is courting them as well, to sell Dreamcast games on the system. We all know that Sony patented a software emulator for the PS2 a couple months ago, and that given the Cell architecture’s computing …