A really fantastic in-depth interview with Valve's Erik Wolpaw has been posted by the NYU Game Center as part of their lecture series. During it Wolpaw plays Portal 2, talking about the process behind creating the game, the motivations behind many of the decisions, and a great deal of thought about how story and games interact. You can watch it below.
This is a hefty interview. It's about an hour twenty. Things begin purely discussing Portal 2, along with watching the opening sequence. That's interesting, seeing a comedy game play in front of an audience. As things progress the conversation broadens, discussing the state of games, means of portraying fiction (including Wolpaw's ingenious idea for including choose your own adventures in games that insist on including books). It's a properly interesting stuff, and well worth dedicating a chunk of your day to.
There's also quite a lot of fun to be had watching as the admiring interviewer sees how uncomfortable he can make the extremely modest Wolpaw with (appropriate) praise. That peaks at about 45 minutes in.
(Oh, and he mentions us, which is rather nice.)