I have a number of regular commuters...

Just weighed the P20 with fenders, rack ,lights, pump, rear panniers, lock, and front bag with my usual gear and it curbs out at 42 pounds... I use this bike for my 100km commute, short tours, and centuries and never feel like I am riding a heavy bike and can maintain a nice cruising speed of 15-18 mph over longer distances. It has some very light wheels which really contributes to it's speediness.

The Moulden monster cross weighs less than 24 pounds with a rack and fenders... stripped nekkid it is a 22 pound bike.

My winter commuter / rain bike weighs 34 pounds with an internal 3 speed and dynahub.

Went on a 85 km ride last Saturday and rode back Monday and figure that I was pushing 60 pounds for total bike weight as I had 4 litres of water and my netbook, 2 days change of clothes, and all my usual crap... averaged 25kmh with some stiff crosswinds for the first 50km and with a little tailwind on the last leg covered the last 35 km in just over an hour.