It seems that anywhere Apple's plans are mulled over, or OS X's open source roots are introduced, there is an immense & bottomless interest in MacOS X on Intel hardware. One can only hope that this interest would trnaslate into a tidal wave of OS purchses if ever Apple Computer released an x86 version of OS X, because they would be destroying 80% of their revenue base in the same fell swoop. Apple is *hardware company* and they get most of their revenue from selling computers, not operating systems.
However, an Intel-version of OS X exists, even if in rudimentary form. MacOS X (the "Yellow Box" environment while the OS was under development) and Classic (the Blue Box environment in OS X) are both well known by now, but development was thought to be halted internally on Red Box (MacOS X on Intel version) shortly before it was completed. This is the reason the MacOS is still around at all (and not an unfortunate anectdote like OS/2): because Apple has wisely decided *not* to release such a version and deep-6ing their hardware market.
That being said, if certain conditions in the industry are right they could quickly release OS X on Intel, but only if they are sure of being able to play on an even field in the OS market on Intel hardware. The principal condition is undoubtedly if Microsoft is restricted from maintaining an unfair competitive advantage by tying Office, IE or other MS products to the Windows OS, probably ensured via breakup as ruled by Judge Jackson. Since this is now unlikely to happen any time soon, don't expect Apple to suicide themselves by competing with a company that holds all the strings. As evidence of this danger, you don't see any other significant market-share competitors around to the MS hegemony, do you? There used to be.
For now, we will have to be satisfied with Apple's open-source Darwin core on Intel hardware. Notably it does not have Aqua, but it is gaining steam as a streaming server platform for Quicktime content, amongst other things. And happily, improving quickly.