No, Nintendo seems to have given us the basics. We're not even sure if Ghirahim is the main villain (and if it was confirmed then I haven't heard of it yet.
As for Brawl, I wasn't spoiled by its site. It's not an all-out adventure title (disregard Subspace Emissary) like Skyward Sword will be. I actually liked seeing who'd be in it (but on the main a friend let me know it by phone...about each time he noticed it was updated). So, I'm content with what Nintendo has displayed so far.