Characters that may have been inadvertently revealed so far are Sweet Tooth, Kratos and a naked, featureless lady.
Nintendo has had a great deal of success with the 'Smash Bros.' series of games. They're equal parts fun fighting game and trip straight past memory lane and right onto the nostalgia superhighway. If you played Nintendo games as a kid, there's plenty there that will spark up those feelings that make you get the NES out of the closet.
If rumors and speculation hold true, and they do more often than you might think, Sony is going to be working on a similar game of their own. Twitter pictures posted and then removed by Chris Molina of SuperBot Entertainment sure make it look like that's the case.
And just who is SuperBot Entertainment? From the company overview, they are "an exclusive developer of Sony Computer Entertainment America and are currently in production of a yet-to-be announced PS3 title."
We're calling this rumor pretty damn plausible.