In an interview with Fast Company, Doug Lombardi, Valve's vice president of marketing” confirmed that we won’t have long to wait because more content will be available in the summer. Sadly, that’s all that was teased, but he did say they’ll be more details revealed shortly.
“We'll be putting more details out about that in a week or so. We'll support that with more videos or more comics.”
In the meantime, don’t forget to check out our Portal 2 review.