Apparently, AMD has plans to have a quad-core processor out by the time Apple goes Intel.

Slashdot Article
Engadget Article (original source)

AMD would just like you to know that by the time Apple’s moved over to x86 in 2007, they’re planning on having quad-core CPUs on the market
Later plans include scalability to up to 32 processors in their devices
The article mentions that of course, most applications are not multithreaded and will not be able to take advantage of this... but my main thought on the matter is that supposing you had a processor intensive application such as a database or some sort of graphics application, possibly even a VM... wouldn't this allow severe performance boosts once you introduced multithread capabilities to the application?. Somewhat akin to scalability in kernel SMP support? Obviously this depends on vendors supporting this feature, but in high end applications, I fail to see why there would not be some sort of support added in, given the obvious benefits and corporate applications for this technology.

If this makes no sense, bear in mind that a: I haven't slept in days, and b: I have no experience in this type of programming.