In a few months (well, ok, a little over half a year), anyone will be able to order, from store.apple.com, Amazon.com, smalldog.com, or a host of other sites, a DVD that will include every binary that makes up a complete Intel Mac OS X installation.
It might be encrypted, it might be that the installer is designed to prevent installation on any machine other than a genuine, certified, Apple Macintosh, but the DVD itself will exist and be sellable over the counter. There's no other way to get a multi-gigabyte operating system update to existing Mac mini, MacBook, MacBook Pro, and iMac Intel users (not to mention Mac Pro and Macserve users.)
And once that DVD's on sale, it will, if it doesn't already enable installation on non-Macs, be cracked. Someone will find a way of getting that disk to work as the base of an install for any compatible PC. It will no longer be necessary to spend a few days (I just downloaded the Debian DVD images, that's two DVDs, and it took nearly a week with BitTorrent) downloading from various dodgy, likely-to-go-down-at-a-moment's-notice, sites and figure out how to get that burnt to DVD and booted. The "installer" will be so small it'll be mirrored all over the world.
So the question here is not the one most Apple fans like much. It isn't "Should Apple allow Mac OS X run on non-Macs?" That's not for Apple to allow. They can make it hard, but they can't make it impossible. The question is "Does Apple actually want to benefit from Mac OS X on non-Macs?"
The real problem at the moment is few people are seeing that. They keep flashing back to 1995, a time when Mac OS didn't have a great rep, when Windows 95 had just come out and was technically better than the Mac OS of the time (albeit with a poorer UI), and when few outside of Mac circles actually wanted a Mac. Moreover, at that time, Mac OS didn't run on the popular hardware of the day. Whether this will be a repeat of that time is open to question given the massive difference in market conditions, but moreover, it's important that Apple make it work if they didn't last time, because they don't have a choice in the matter.
It wouldn't surprise me in the least if Dell and Apple are putting together a "solution" for people who want Dell hardware with Apple's software. If Apple makes deals with individual manufacturers, it at least has some control over what's going on. It can, at least, manage the experience, and ensure that they definitely see a slice of the revenue for all Mac OS X using machines.