It seems my suspicion about Snake being a character in Playstation All-Stars is happening. I really think Sony should have held off on adding third-party characters for a sequel, especially considering that this game is going to be released very late in the PS3's life. Having all of Sony's major characters in one fighting game would have been the draw for the first game, while having third-party characters that were prominent on Sony's platforms (Snake, Lara Croft, Cloud, etc.) would be the major draw to the sequel.
I am now wondering if Snake will be brought back.