I also hope Canon wouldn't put IS in a 17-40 lens just to boost the price. For a lens whose primary use is on a tripod, that would be silly
I hear you there. but their current trend of releases tends to suggest that, if they do update the 17-40, it will most likely have IS built in.
that being said, I'd dispute the fact that the majority of its buyers use it on a tripod. I know lots of people that use the 17-40 specifically as a wide-angle walk-around (or hike-around, rather), and would love to not have to bring their tripod along.