Retro Studios' twitter proclaims that  we'll be "pleasantly surprised" in just a few hours. So, is it a new Metroid (but not Prime) title? Is it a First Person Shooter/Adventure based on a new IP altogether? Or is it something completely different like a 4 player split screen badminton simulation? What do you guys think?

Edit: Um, the horrible grammar/spelling/syntax makes me think it may be a fake after all... It wouldn't be hard to do, yeah?
"Welcome everybody to Retro Studio's official twitter account. Here you will find information and some tidbits about our upcoming games."

A new Metroid game sounds good but yet unlikely .

Bleh, see the edit... Let's hope that's not the case.

I knew it was fake because Nintendo WILL NEVER inform you of ANYTHING until their ready to show something off.  There will never be a leaked rumors thing by Nintendo because they are very protective about this information.

If it was by Retro it wouldn't be a leak but an announcement of an announcement :P