If you're wondering why his character died on House last night, you now have your answer. Kal Penn (Harold and Kumar) asked to leave the show to take a new job with the Obama administration.
In an interview with Entertainment Weekly, Penn says that he met Obama during the campaign and was since offered a position as a public liaison:
I got to know the President and some of the staff during the campaign and had expressed interest in working there, so I'm going to be the associate director in the White House office of public liaison. They do outreach with the American public and with different organizations. They're basically the front door of the White House. They take out all of the red tape that falls between the general public and the White House. It's similar to what I was doing on the campaign.
Penn says that's he's not necessarily retiring from acting, and that the time-span of his White House job is unclear, but that he does plan to pursue a career in politics for the long haul. So, good for him.