You can go here:
Injustice: Gods Among Us - Announcement Trailer - GameSpot.com
For the "full" scoop. Nothing else is known about it besides that it is a fighting based from the developers of the Mortal Kombat franchise.
Other useful links:
INJUSTICE
https://www.facebook.com/injusticegame
Characters include:
Batman
The Flash
Superman
Harley Quinn
Solomon Grundy
Wonder Woman