Running Mac OS X in that state is completely stupid, because it's running in a totally unsupported and un-updateable state.
While you personally may argue that all you're doing is legitimately running Mac OS X as a guest on Apple hardware under Boot Camp, 99% of the people running it will be doing it completely illegally, against Apple's license agreement, on non-Apple hardware, and with pirated copies of Mac OS X.
I discuss the general issues
here, which are:
Ignoring the technical hurdles for a moment, and though it actually wouldn't be against any license agreement to run Mac OS X in a VM *on Apple hardware*, the Apple license agreement expressly forbids running Mac OS X on anything but Apple hardware. This means that if a commercial VM vendor started doing what was necessary with their product to run Mac OS X in a VM on Mac OS X, they'd be treading dangerously close to potentially allowing it to run in their VM product on other platforms where it wouldn't be running on Apple hardware. Also, as I said, there are technical hurdles to be overcome.
(And yes, to anyone who may be reading, we're aware that Mac OS X (Intel) has been hacked to run in, e.g., VMWare on PCs already for quite some time, but this is DEFINITELY against the license agreement (that Mac OS X can only be run on Apple-labeled hardware), requires hacking Mac OS X and running it in a completely unsupported state, technically requires pirating Mac OS X since no way to get a standalone license for Mac OS X (Intel) exists, and may be illegal in certain jurisdictions.)
Because of the general situation, I don't think any VM vendors are going to be supporting Mac OS X as a guest OS, even ONLY on Mac OS X on genuine Apple hardware, until they get a specific blessing to do so from Apple, and/or partner with Apple on this. However, Apple may be planning to offer its own virtualization that does support Mac OS X/Mac OS X Server itself with Leopard, and therefore may not even get involved with third parties.
and
No *commercial* vendor (like Parallels) is going to this unless:
1.) They have a specific agreement/partnership with Apple to do so, or
2.) They can GUARANTEE to Apple's satisfaction that it will only allow running Mac OS X VMs on a Mac OS X host on Apple hardware only (see 1.)
If any product makes it substantially or even marginally easier to use Mac OS X on non-Apple hardware in any way, especially if Mac OS X can remain unmodified in such a hypothetical situation, Apple would come down on that product/company like a ton of bricks. Whether you think they're right or wrong or justified in doing it is irrelevant; they would, and the vendor - even if it's someone like EMC (VMWare) - would have no hope of defending themselves. The reason this would be the case is that any capability to allow Mac OS X to run on non-Apple hardware wouldn't be incidental; it would be SPECIFICALLY engineered into the product for that purpose, and such a capability directly violates Apple's EULA; or, rather, allows, and indeed would encourage, a customer to directly violate Apple's EULA.
Now, if a vendor made a product that passed the TPM calls from Mac OS X (Intel) to TPM hardware on Apple hardware only, that would be a virtualization solution Apple might stomach, as it doesn't really change the landscape. But to do this, there would be significant technical hurdles, especially for a product like Parallels Workstation, whose emulated hardware profile is nothing close to what Mac OS X (Intel) needs to boot. Then, there's the other problem (which, yes, would be going away with Leopard) that there is no legal way to obtain a standalone licensed copy of Mac OS X (Intel), which therefore still requires it to be used against its license agreement.
No commercial vendor that values its existence is going to wade into this rat's nest, *unless* it's Apple itself, or some vendor partnered with Apple on this, specifically. Trust me.
Supporting the community that hacks Mac OS X in this nature (e.g., to run on non-Apple hardware) is hurting Apple, whether you yourself think you are, or would like to believe it, or not.
And no, to anyone who thinks they are, *you* aren't in a position to decide what or what doesn't hurt Apple with regard to the appropriation and use of their products. Only Apple is. Some governments give Apple legal frameworks in which to back this up, such as civil or criminal penalities for violating license agreements, reverse engineering products, or circumventing digital rights management (which is central to Mac OS X (Intel)'s boot process). Apple is the entity that spent billions of dollars in R&D, years of work, and tens of thousands of manhours in the development of the product. Have a little basic respect for the work of others.
Now, if someone with an Intel-based Mac could successfully independently modify their copy of Mac OS X themselves, without any outside assistance, to run in a configuration of their choosing, I'd say more power to them. But if you rely on the hacking community to provide you with such solutions, you're creating demand for and supporting a community that is geared toward using pirated copies of Mac OS X illegally on non-Apple hardware. (Hint: no, this isn't a "good thing" for Apple by making people "fall in love" with Mac OS X. Remember, you don't get to decide what's good for Apple. Apple does.)
To get on-topic here, it's certainly within the realm of feasibility, especially given Apple's product line and its predictable and finite range of graphic card offerings, to support 3D accelerated graphics via virtualization. In fact, this is on the roadmap for Parallels Workstation in the future (though perhaps not in 2.1).
As has been discussed here before few of us think it is likely that Mac OSX will ever be a (legal) guest OS for Parallels.
