Not sure on all the details, but even a free account can get access (I suspect it is region-restricted, but no way of knowing).

http://www.fileplanet.com/promotions/dcuniverse/

PC and/or PS3 "beta" available.

So everyone get to playing the "beta"!

On a completely unrelated note: It really annoys me that so many games use "public beta" as a way to provide a demo without getting yelled at for bugs.