I think this is a good move for Apple, and it's going to sell more Macs for them. I ran into two examples at work yesterday.
First, we're looking into adding a new computer lab for running Maya, and the plan to this point has been to get PCs. One of the reasons for this is that by the time we can purchase them, the G5s will be gone from Apple's line-up, and Autodesk hasn't announced a Universal version of Maya yet (if ever). Now, this gives us an opportunity to get Macs, and still run Maya on them whether or not a Universal version is released. So there's a potential of 30+ Macs right there that wouldn't have been purchased otherwise.
Second, one of my co-workers is a long-time Windows user, and is one of the only people in my department with a PC on her desk (we're almost completely Mac-based). But now, she wants to get an Intel MacBook because she can still run Windows most of the time, but also start learning OS X and be able to integrate with what we're doing on Macs.
Good for Mac gaming? I don't know. I almost never buy Mac games anyway (sorry Brad), but that's because when I buy games, I buy them for my PS2. Certainly, I think that if it's easy to install Windows, if Windows runs well, if Mac users can stomach running Windows, and the Mac port of a new game is nine months down the road, then yes - this could hurt some sales of Mac games. But I think most Mac users who are hard-core gamers already own a PC or console and do most of their gaming there anyway. So if anything, this may sell more Macs to those gamers who just buy PCs for gaming machines, which is a good thing.
What I think is really needed from the Mac gaming community is more original games for the Mac. (Yes... I'm still pining for an OS X version of Battle-Girl.) Then as the Mac market grows (and I think it will), there will be games compelling enough for users to boot into OS X and stay there awhile.
The other thing to remember here though, is that right now, only a very small percentage of Mac users have Intel Macs. So there's time to see the effects of this transition, and plan accordingly. It's not going to be all-Intels overnight.