In a recent interview, Valve marketing VP Doug Lombardi announced that Portal 2 DLC will be coming this summer, with details of what to expect from the content arriving shortly.
“We will be announcing some DLC for it, so folks can keep a look out for more content coming this summer,” said Lombardi. “We’ll be putting more details out about that in a week or so. We’ll support that with more videos or more comics.”
It’s rumored that the DLC announcement should be made “before this week is over,” but Lombardi didn’t reveal any further details on the DLC. The most logical guess is that the DLC will expand on the co-op portion of the game, but as it goes with Valve you can always expect the unexpected.