Super Girl is one of those characters from the DC Universe that gives me a headache when I try to read up on her backstory on Wikipedia to give you some form of background in this news piece. Do it yourself. I haven't had enough coffee for my brain to interpret quotes like "[t]he 1985 limited series Crisis on Infinite Earths eliminated Earth-Two, causing her origin to change; she became the granddaughter of the Atlantean sorcerer Arion. However, story events culminating in the 2005-2006 Infinite Crisis limited series restored her status as a refugee from the Krypton of the destroyed pre-Crisis Earth-Two universe."
Anyway, Power Girl will appear in SOE's DC Universe Online and here's a couple of screenshots and renders with her in.