What you have to do instead is get hold of an ISO image of Leopard, apply a patch to get that image to install, and then essentially fool the PC into loading the whole thing from a USB drive.
Add to that the fact that Leopard comes sans most of the drivers you're going to need to run your PC's sound and video cards, and you get back to my original thesis that the real reason this hack is so popular is simply because it's there.
If you're wondering why I'm conflating one hack with widespread interest, it's because the DailyApps posting is only the tip of the Leopard-on-PC iceberg. There's a flood of stuff on the InsanelyMac Forums alone, including this discussion of how to squeeze Leopard onto a single-layer DVD. Over at the OSx86 Scene Forums, someone has posted a guide for installing Leopard on a "Hackintosh" (i.e., a PC which you're trying to hack into a Macintosh-like state).
Lest you think all of this is some kind of hack come lately, think again. There's a long and legitimate history of installing OS X on x86 hardware, much of it helped along by the OSx86 Project. Of course, we should thank Steve Jobs, since none of this would be possible if he hadn't moved the Mac off the PowerPC architecture onto X86 in 2005. (OK, it would be possible, but not too prevalent, because we'd be talking recompilations of purloined source code or virtualized implementations, etc.)
It won't surprise you to note that nearly all of the hacked-Leopard-on-PC material works off the assumption that you've stolen your copy of Leopard (i.e., you've downloaded it via the peer-to-peer BitTorrent network). There are no recipes for taking a legitimate retail copy, purchased at the Apple store, and repurposing it onto your PC. Probably this has something to do with the fact that Leopard costs $129 at retail.
Interestingly, Leopard's pricing points up a key difference in the computing culture between Apple fans and PC folk. As we saw during the iBricking fiasco, the former are pretty much willing to pay in tribute to Steve Jobs however many greenbacks he wants, without too much regard for what they're getting in return. In contrast, the PC ethos is that you never open your wallet, even (or especially) if it's the right thing to do.
At the same time, you have to give the Apple people their due, in that they're apt to engage in lively debates, like the one which broke out in the comments section of the DailyApps post. Readers were wondering why Apple doesn't make OS X available for the PC.
That's a reasonable question, until you realize that, while it'd be good for PC users, it'd be bad for Apple's business. There'd be no reason to pay a premium for Mac hardware if you could get the same experience on a cheap white box.
Me, I think I'm going to go buy Leopard (normally, a site like this would get a courtesy review copy from the vendor, but that's another story), figure out how to convert the .dmg files to a burnable ISO image, and do an install on my PC. As to whether Leopard or Vista will work better on my PC hardware, I can tell you now, but I'll definitely report back on which OS looks better .