Well, either way you're going to need to buy a lens of some sort. So the question is whether to go with the 28-135 or something else (like the cheaper 18-55 kit lens, or the 17-85 that's often bundled -- or jump right to the 24-70L...etc.).
Oddly, it's looking like neither
Adorama nor
B&H are providing the $200 instant rebate on the 40D package with the 17-85...wonder what that's about.
In any event, I went with the very basic 18-55, and was happy with it -- it cost almost nothing (at the time, it was an extra $50), and allowed time to decide what types of shooting I preferred and (importantly) how much money I wanted to sink into it. I immediately bought a 50mm 1.8 to go with it, and that worked well.
The 28-135 is, by all accounts, a good lens -- but the one caveat is that on a cropped sensor (like the 40D) it may not be wide-angle enough. 28mm-135mm on a 1.6x crop is equivalent to a 45mm-216mm lens...and that's not necessarily a great focal range for general walk-around shooting.
Good luck!