For anyone that's interested, go here -
http://orange.half-life2.com/portal.html and check out the trailer, it's brilliant and will make you go buy the game.
And for those that aren't going to buy the game... search YouTube for the ending to Portal, it's the bestest bestest end to any game ever. Ever.
Edit: If you ARE going to buy the game, please don't check out youtube for the ending, it'll spoil it's sweetness completely!