Street Fighter's Ryu is almost certainly coming to Super Smash Bros. (SSB). Multiple files featuring the character have been extracted from a recent update, adding weight to a rumor that began back in April. The evidence is pretty compelling: there's a video (below) that seems to be Ryu's victory sequence, an image depicting what appears to be a recreation of his stage from Street Fighter 2 and a selection of color options for the character.
Capcom (which owns the Street Fighter franchise) has already licensed Mega Man out for SSB, but Ryu would be the first character from the legendary fighting series to make its way over to Nintendo's brawler.
In addition to the Ryu leak, a video pulled from the same update shows Fire Emblem's Roy -- a character that previously starred in Super Smash Bros. Melee for the GameCube -- slashing his way around, meaning we will hopefully see at least two new characters announced at Nintendo's pre-E3 SSB presentation, which kicks off at 10:40AM ET tomorrow.