But seriously, in case you think that I'm just some PC zealot who can't be trusted, take a look at this News.com article about analysts' reactions to Jobs' announcements. Regarding the dual processor box, one analyst says that "Mac OS doesn't do anything with the second processor, and most Mac applications don't do anything with the second processor." I sort of suspected that OS 9 didn't support SMP, but I wasn't sure so I didn't say anything.
The article also points out that "Offering a second processor for free is also a way of drawing attention away from a larger problem. While Intel and AMD have reached clock speeds of 1 GHz, the PowerPC G4 hasn't budged beyond 500 MHz." Gee, sounds a lot like what I said.
Don't worry though; buy a dual CPU Mac now, and according to current estimates, it'll only be another 6 or 7 months before your operating system supports it; that's when OS X is supposed to hit the shelf. But until May of this year, it was supposed to be out this summer, so who knows.
Maybe by then, Motorola will be able to produce chips over 500 MHz in quantity-- the article mentions that they demonstrated a 700 MHz G4 all the way back in October. Of course, if we're talking current estimates, by early next year, Intel and AMD should have chips in the 1.4 to 1.7 GHz range, running at 200 MHz + bus speeds, with at least 133 MHz DDR RAM with 266 MHz of bandwidth. If only those guys would stand still for a while, Motorola might have a chance to catch up.