Any worries about Linux being eroded by Mac OS X now that Apple have moved to Intel does indeed look like utter hogwash, as Apple have confirmed that Mac OS X will not run on Intel-based machines sold by other PC manufactures: it will be tied exclusively to Apple hardware. Apple vice president Phil Schiller confirmed at the recent World Wide Developers Conference that there is not a chance in hell of Mac OS X running on anything other than an Apple Mac.
It's believed that Apple will likely add a specialized chip to the motherboard of its Intel-based systems that the Mac OS X must first detect prior to booting. Either that or the company will contract a proprietary motherboard chipset from Intel that will perform a similar function.
However, don't rule out the possibility of Apple Macs being able to run Windows - this is indeed very possible. Just imagine being able to tri-boot Windows, Mac OS X and some Mac compatible Linux on the same Powerbook! Yum!