Champions Online Official Site
I cut my MMO teeth on City of Heroes so I'm quite excited about this one. I also played a few sessions of the Champions pen and paper role playing game back in the day, was a very flexible point based system if my memory serves.
It's being developed by Cryptic who did City of Heroes and City of Villains which they'll probably wind down once Champions goes live. The good thing about the City of Heroes MMO was it's fast paced action heavy combat and it looks like they're going to try and push that even further in Champions. The visals also look much better, from what I can see in the screen shots the cell shaded style is one of the best attempts I've seen at comic like rendering.
I've picked though the dev posts and thus far they're mostly keeping mum about the details. They don't want to announce anything untill it's 100% going to feature in the final game. Aparently they made a lot of promises with City of Heroes that they never really delivered on and they don't want to dissapoint anyone so this time around they're playing things closer to their chests. However, a few detials have emerged. The max team/group size will be 5, down from 8 in City of Heroes, but you'll be able to form raid-like groups with multiple teams of 5 and there will be even more character customisation options including the ability to choose custom colours for your powers.
I can't wait for the beta.