Portal 2 has been confirmed for release.
This isn't some remake, it's a full-on sequal set a few decades into the future. GLaDOS is back and as insane as ever, and she's out for revenge...well...sorta...it's kinda hard to tell with lines like this:
"We're a lot alike, you and I. You tested me, I tested you. You killed me, I kill-oh. Wait. I guess I haven't killed you yet. Oh well. Food for thought during this next test."
In addition to new puzzles and more than double the length of the last game, this one offers Co-op mode. One player controls a modified Personality Core (The things you had to rip off GLaDOS in the first game) while the other controls a walking turret. Each one is able to fire the two standard portals, allowing four portals to be active and used by both players at a time.
In short, if you haven't already planned to, go buy this game when it comes out. (No official release date yet. Just sometime in the fall) And if you aren't planning to buy this game, your life is void.