"I wonder what kind of hats this collaboration will bring about..." - howlthorne
It looks like the Shacknews community hit the nail on the head. Adult Swim and Valve's collaboration has been revealed... and it is a hat. No, not a hat you can wear in real life, silly. It's a free "limited-edition" Robot Chicken hat for use in Team Fortress 2.
The hat is being distributed to subscribers of the Adult Swim newsletter. "If you signed up and confirmed your account by midnight 6/27/12, you will receive your code on 6/28/12. If you signed up after midnight, you will receive your code 7/5/12," the official FAQ reveals.
While this may not be the Team Fortress cartoon we all wanted, Adult Swim is continuing the dangle the Valve carrot in front of friends. "This ain't the last you'll hear from Adult Swim and Valve. Stay tuned," the promo site teases. Oh, so we can get even more hats? We won't fall for that--oh wait. Look at this curious part of the Q&A, as discovered by Joystiq:
Q. Are you making a Team Fortress cartoon?
A. Go ask your mother.