I've been thinking about this more lately (mostly as I listen to ATP) and wonder what Apple's through process when it comes to the Mac Pro.
If Mac Pro is such a small part of the market and desktops are also such a small part of the market do they need to ditch the Mac Pro entirely (or subcontract it out to one of the other vendors).
Consider for a moment we know that OSX can run in a hacintosh environment pretty easily, why not take the normal business approach, certify the Intel stable chipset, mandate Xeon CPU's and partner with a GPU provider for certified drivers/models and let people build their own Pro machines.
For me this approach leaves a few questions.
1) Can Apple limit the hardware enough so as to ensure minimal issues with OSX updates/upgrades?
2) Can Apple limit the hardware enough to ensure you can't simply build your own standard desktop machine?
3) Even assuming 1&2 are possible, will this cut into their own hardware sales too much?
4) Is this a perception they want in the market for "Mac Pro Compatible" machines... (which may be viewed as a very slippery slope)?
So under this concept, you couldn't build an i7 based system and load up OSX but you could build a Xeon based machine (maybe even with a minimum number of physical CPU's or cores) and away you go. Maybe even a special paid "OSX Pro" install if that's what it takes.
Hopefully the consumer market would still buy the simple and easy iMac's and the pros could build their own.... although I do see 3rd party companies building the lowest spec Xeon machines that meet the spec and flogging them off as off the shelf Mac Pro machines...
Either way it's an interesting thought.