You can head over to their website to sign up for the beta, which is now open; you’ll have to sign up for an account on the website first, though. Click on “beta preview” in the upper right-hand corner to sign up.
Here’s the description of the game:
Based on the award winning Champions setting from the HERO System of pen & paper role playing games Champions! taps into the rich universe of heroes and villains with unparalleled intrigue and adventure. One of the coolest elements the game offers is the unique character customization tool the player can create their own characters as one-of-a-kind superheroes, where gamers can choose from thousands of costumes, body types, power sets, and character appearances. Furthermore, while players transform into the ultimate hero, the Nemesis system lets Champions Online’s powerful customization tools craft an enemy of the extreme opposite, a villain of nightmares. The story of Champions Online is constantly changing, continually evolving. Villains are defeated. Heroes rise and fall. Cities transform. Your actions may decide the future!
I never played the old school pen-and-paper version, but I remember the comic from Eclipse that featured Foxbat, who apparently is in the online version as well.