While it's true I haven't a clue about Apple's internal strategizing, I would think that putting a G5 in the consumer line-up would be good for public relations. The perception that the PC has it over the Mac due to high clock speeds, et al, would be mitigated in some part by being able to say you can get a consumer-model 64 bit system. Given that the PC world is not really ready to go toe-to-toe with the Mac in the 64 bit environment, this would help demonstrate Apple is pulling ahead.
At this point, you have to obtain a (probably expensive, don't really know) 64 bit version of WinXP Pro or go with a 64 bit version of Linux if you want to run a 64 bit PC. Then, given the fact that there are two different implimentations of 64 bit computing in the PC world (AMD and Intel), what about compatibility? Maybe it's an issue, and maybe it's not, but it has gotta mean different optimizations. Then, that only gets you over the OS hurdle. On the Intel 64 bit implimentation, you really lose compatibility (if I remember rightly, or at least sacrifice performance) if you run a 32 bit app. The AMD implimentation I don't think necessarilly takes a performance hit, but you don't get a benefit if you continue to run 32 bit apps. As far as running a 64 bit Linux OS, I don't know how that's working out at this point.
The point is that at the moment, 64 bit computing in the PC world isn't as high a priority as it is on the Mac platform, and you really don't have a lot of opportunity if you are a typical "mere mortal" user to use or benefit from it. On the other hand, this leaves Apple in the supremely desirable "cutting edge" position. In other words, this gives significant and meaningful bragging rights.
Remember something else: Microsoft is still largely gearing up for continuing to function in the 32 bit processor space. I don't know what Longhorn will bring to the table on this (I can't imagine Microsoft is ignoring 64 bit computing) but it doesn't matter because by the time Microsoft "begins" to put out a 64 bit OS, Apple will already have a proven track record, years of experience, and an OS that is fully "ready for prime time". And, more to the point, Apple will have a much higher market penetration of 64 bit computing.
And, speaking of Linux/UNIX, don't let's forget the fact that the improvements in that OS environment will bleed into future versions of Mac OS X. Again, Apple stands to directly profit from both it's own in-house innovations and the innovations of the Linux/UNIX developer community. This is all IN ADDITION to the fact that if you run a non-Windows system, you also don't have to worry about all the hacking and VBS-based viruses, etc., that you do if you are a Windows user.
Lastly, in my position of telephone tech support for a major PC maker (sorry, folks, but I gotta earn a living somehow), I can tell you for a fact that the majority of people I talk to who use Windows hate Microsoft, and everything Apple can do to twist the screws further will only help them in the end. Believe me when I tell you that, in large part, if our customers could walk away from Windows, they would do it. And, if Apple keeps doing what they're doing, our customers may well become Apple's, along with many from other PC manufacturers.
Just my 2¢.
Mike