Not sure if this has already been pointed out, I had a look but I couldn't see if anyone else had posted it.
You can download the soundtrack for free from http://www.thinkwithportals.com/music.php
It's very good, I have been enjoying it thoroughly. I can't wait to be finished with University so I can play the game again! In 2 weeks time I be finished with a degree with Honours in Computer Science, yay! Got a job lined up as well, yay again!
Just an insight in to my life there, anyways enjoy!