Super Smash Bros. Brawl
I just ordered mine today. No telling when I'll get it, but I'm really excited. I've always been a fan of the Smash Bros. series since N64.
This release features loads of new characters. Some of the choices are different. I would have never expected Snake of the Metal Gear. "Pokemon Trainer" is an interesting choice. No name, just Pokemon Trainer. Maybe Professor [insert plant here] will ask you who you are when you choose this character. You can finally play as King Dedede and Pit now. No Ridley yet, of course. Ridley is a boss in this version at least.
The stages are apparently going to be much more interactive in this release, including destructable terrain and time-based events. You can create your own stages now for the first time as well.
Last really new feature is the online play. It includes the familiar battle modes and a few other new contests. The ability to spectate and bet coins on matches is also available.
I'll post a followup once I get my hands on the game.
You can find more information at Wikipedia.