[tabascobobcat]

Ask the alignment guy when the last time his equipment was calibrated. I actually saw a tech back a car off the lift with all the sensors still mounted to the wheels.
If it's not tire pressure, not the alignment and not a dragging brake (you would have likely burned the pads and rotor by now if it were) then it's most likely the tires like Steve said. The tires have a property called conicity (derived from the word conical). Basically the belt overlap can cause the thing to have a slight cone shape to them. Newer cars are ever more sensitive to this than were the older ones. If switching the front tires left to right doesn't work it may be the gear box, subframe, tire RCF or RAT, etc....