OK, so here's my crazy bit of speculation: Apple is pleased as pie that something hacked OS X on Intel. Crazy? Hmmm... let's think....
First, this is a developer build, and having it running around in the wild isn't such a big deal. It isn't going to cannibalize sales of anything except maybe a few developer machines that Apple's just leasing to developers anyway. I doubt they were hoping to make a fortune on those $999 machines. They are no doubt subsidizing them, actually. So the more developers that manage to get the kit running on their own machines, the better. Any serious developer will still have to have at least one Apple kit to make sure their stuff runs right. If anything goes wrong, Apple can always try to break the rogue copies in the next update.
The hacked version has a huge upside, though: the geeks who manage the install and run OS X on their own machines are exactly the kind of people that Apple should want running OS X at this point. These are the guys and gals who will write programs and utilities, replicate their favorite Windows stuff on OS X, and generally insure a robust software environment when the first machines come out. On the other hand, they are insignificant from a financial standpoint.
When the Intel machines hit, 99.9% of the buyers are going to be people that wouldn't even consider running a computer with an unsupported operating system that may or may not totally work right. No business user can afford to and hardly any home user would want to let alone know how to. Lost sales are not an issue. But the ranks of the teen geniuses who have the time and energy to get OS X running on their aging Dells are exactly the kind of people that may produce the next killer app, and Apple should desperately want them to fall in love with OS X. Finally, they will have a way to allow that to happen, without having to in any way compromise their "we make the whole widget" ethos.
By officially saying OS X cannot run on anything other than a Mac, and making it pretty difficult to circumvent that, but not doing very much to stop those who can figure it out, Apple gets the best of both worlds.