I have a X41 Thinkpad that is 2.73 pounds. I love it! Especially the neat fingerprint reader. No more passwords! And the 802.11 A/B/G integrated WiFi is handy.
The strange thing is that when I pick up my laptop bag, I keep thinking in the back of my mind that I've forgotten my PC. My previous T40 was pretty heavy and I got used to lugging a lot of weight around.