Apple is stupid on this issue
To go as long as they did without a major update to what was the flagship of the company, then release a dud of an update, but have rumors that a new desktop mac is coming in a year? If Apple does in fact have plans to continue the Mac Pro line, they should drop the secrecy that gains them a few marginal sales of current models and just say so. So what if it caniballizes a few sales of current models; the alternative is they lose the customer to Windows, possibly forever.
I'm still using a 2.66 dual Xeon, and I'm long overdue for an upgrade. I worry that my machine won't like Lion, so I'm still back at Snow Leopard. I am like many other people at a platform crossroads. I might be inclined to tough it out on my current machine if I knew there was in fact a true upgrade coming, but rolling out a lame update and then saying nothing else makes me think they're done with it and I'd be a fool to stick around waiting.
The mistake is treating it like a consumer entertainment device rather than the work tool that it is. People need to plan on technology in their business, and with Apple/mac/OS X, it's a lot more than just the hardware. Sure, I could build a Windows box, but I'd also have to replace $10k worth of OS X software. It's not like 1996 when the sum total of your peripherals and software was less than $2k.