Yeah, but I've read that you can update via software update with impunity.
I don't understand what the system update has to do with piracy. (Are you talking about something else when you referenced me stating the Dell install uses the real leopard dvd?)
With the dell method, it works with a retail Leopard dvd. As part of the Leopard install, if the dvd you used to install is not the 10.5.6 update you have to download and install that update as well.
After that the normal software update works like a real mac (at least so far, never know about future updates.)
The install requires a retail dvd, and not an internet-downloaded modified version like some other computers.
Is it legal? Well, you have to go to a store and buy Leopard, just like Windows or any other OS. Apple gets money for it's software just like you purchased it for your Apple made computer.
Is it violating the EULA? Yes, as apple states that their software is only licensed to run on Apple hardware.
Is a violation of the EULA illegal? No one knows. The courts are working this issue out now with the Psystar-Apple lawsuits.
Do I expect Apple to eventually do something to ensure only real Apple computers get update? Yes I do, especially if the lose the Psystar lawsuits. Imagine the number of unauthorized "clone" manufacturers that would sprout up overnight. If they follow Psystar's model of including a retail dvd with every install, they would be just as legal.
However nothing would prevent Apple from doing system checks in the future to ensure it really is Apple hardware before it allows an install. The only reason I think Apple hasn't locked down the OS is that you can't go out and buy a Hackintosh (except Psystar.) If Apple loses its lawsuits, I expect Apple will react quickly to prevent installs.