Tell your LBS ******* about my Steamroller. It's plenty light.

http://web.mit.edu/psn/www/step2/IMG_0713.jpg

[Edit: Ok, I concede that the frame is hardly the lightest thing ever, but unless you want to blow through the 15 lbs. barrier, you can still make a Steamroller pretty light, i.e. less than 16.5 lbs when I'm done.]