I'm not sure if there's been a thread about this, but I didn't feel like sifting through all the late Activision hate to find it. So, SuperBot posted this and I think it means 2 things.
1. They're giving out a month of Playstation Plus, which could only mean we have a PS+ Beta/Demo coming within the next month.
2. "INVASION". This is the name of the leaked Killzone stage. So we know that'll get shown there, and my guess is no new characters and just the 3 remaining stages (the other 2 being Black Rock Stadium and Columbia).