Wow, some great responses, thanks to all. I recently rented the 15-85 and I don't know if I have a bad copy or not, but I'm not very impressed. I find there's a lot of distortion at the wide end. I may rent the 17-55 and see what's that about before I make my decision. I just purchased the 10-22. For you prime people, How do you find the canon 24 usm is and the 28 1.8 vs 28 usm is? Or even the 35 usm is. I know they're not very wide but how do you feel as a day to day lens on the crop body.
Anthony, I have a 7D. I waited forever for the long rumored 24-70 f/2.8L to be updated with IS. After waiting a year I pulled the trigger on the EF-S 17-55 f/2.8 IS USM. After a few days with the lens I wished I would have purchased it a year earler. This lens was made for crop cameras and is the 24-70 FF equivalent (only it has IS). I wouldn't hesitate to get this lens.
I have a friend that purchased a EF-S 15-85, and we were shooting at an indoor church social (flash not usable) and he couldn't get any pictures because of the higher f-stop. Later that week he sold his 15-85 and purchased the 17-55. For me, the wider aperture trumps the longer focal range every day.
Even if I had a FF camera, I would still keep the 17-55 as long I had my crop camera. If I sold the crop, I would sell the lens with it. I don't buy into the concept of limiting my lens selection to EF only in the event that some day I may end up with a FF camera.
With the 17-55 f/2.8, I don't see a reason to get any primes that are not faster than f/2.8. So the new 24 & 28 f/2.8 IS primes dont add anything beyond what you already have with a 17-55.