Yes, I've said this before, with Sonic @ The Olympic games being released, I see no reason why Sonic won't be in Brawl. Also, Snake is a confirmed character and he's 3rd Party. However, it's up to the team at Sega, Miyamoto has already said 'Yes' to Sonic. It's too bad, I don't like the idea of Sonic in Brawl.
Just a note, in the future use the Search Function.