It's called Cyberstalker and stars Mischa Barton as a woman being stalked by a mysterious stranger who murdered her parents. (I found out about it from an interview Dan did on NPR in January.)

You must watch it as it features Dan playing a wheelchair bound nerdy computer programmer with suburban-dad-hair and boxy Oxford shirts who talks in tech jargon the whole time. Also, he's the stalker, and is not actually wheelchair bound. I'm not sure why I'm spoiler tagging it, because if there's one thing this movie isn't it's subtle, but it's worth knowing because it just makes the experience of watching him in it so much funnier.

I spent an instructive half hour watching only his scenes and it was hilarious. The video is crappy and has the beginning and end cut off, but who actually cares.

EDITED: I just want to emphasize- the movie is not great, but he's actually pretty good in it! It's more that it's just so entertaining to see him play a type so against what we're used to.