I worked on this at Valve. It was a super quick turnaround, but im pretty pleased with the result! Now that Portals bin out for a bit im posting this on my vimeo so i can get a high quality version here. Theres lots more of this stuff on Valves youtube channel and I couldnt reccomend highly enough! that you go check it out.

http://www.vimeo.com/23030909