... and then maybe get the older ones cheaper, even though it'd still take some time before the new ones ship.
Ceterum censeo: Apple should update the PowerMacs DEFINITELY more often than once a year. The 'upgrade' of the 1.8 GHz to a dual doesn't really count here, because the highend machine wasn't changed.
If, say, Apple releases a 3.0 GHz this Summer, I _bet_ more people would've bought a 2.5 GHz PowerMac G5 in the first half year than people bought 2.0 GHz now. I mean, look at your question... Wouldn't it be easier now if there were 2.3 and 2.5 GHz machines around for you to buy? The step wouldn't seem so hard...