For what it's worth, 99.9% of MOST people's computing experience on a Mac Pro barely makes use of the potential power these current '09 machines have.
All of you clamouring for a new model need to ask yourselves how more cores are going to help you? The real benefits, from any new model, will probably come from USB3/GPU options etc.
The 'snappiness' of the system isn't limited by the hardware these days, but the software - and we all know, that the software barely makes use of the cores - or, when it does, it's only during a long processing task anyway or working with audio in a sequencer in real time.
As a designer, I'd sure love my mac to be even faster, but honestly, none of my design/web software comes close to making use of all the power I have in my 8 core 2.93Ghz Mac Pro. In fact, I don't think software will be able to make full use of this machine for another couple of years, once developers are more capable of writing for multiple threads and harnessing the power of Apple's new Grand Central and Open CL etc etc.
It's sure nice to have the latest and greatest Mac Pros sitting on your desk (trust me I usually buy the latest and greatest), but this machine is no faster (in feel) than the 2008 Mac Pro I had, and the 2006 one before it. They're all about as snappy as the last. Time for the software to catch up