It's almost a no-brainer that Valve would be providing post-release downloadable content for Portal 2. The developer has always been good about releasing new (and free for PC owners) content for its games over the year. However it's always good to get the official word that new stuff for the puzzle shooter sequel is on its way in the near future,

At the end of a (spoiler filled) interview with Valve team members on the Fast Company web site, Valve's marketing head Doug Lombardi states, "We will be announcing some DLC for it, so folks can keep a look out for more content coming this summer. We'll be putting more details out about that in a week or so. We'll support that with more videos or more comics." Hopefully we will see stuff that was cut from Portal 2 that was shown in the game before its release such as the Pneumatic Tubes.