You can make a dual quad xeon for around 1500 or less. I did but the chips are 2.5 ghz from ebay, no cd drive and no graphics card. Seems the price of xeons go up above 2.5ghz. Not a fan of hyperthreading so not sure if my next build will be another harpertown or shoot for the i7 xeon.

A single socket i7-920 Bloomfield at 3700+ will outdo a dual harpertown of the same speed by quite a bit and use less electricity doing so.
I have 2 dual Harpers here, one with X5470's( best harpers money can buy) and one with X5460's and they do between 29-33K a day.
The i7 will out do those numbers.
Do a X58 board with the upcoming 6 core's from Intel..Not much longer of a wait..

The 6 core Westmere's won't be anywhere near $2500.00..
Not even close..Trust me..

Another point and this isn't just pointed at you.
If you always look to the future you will always see something that is possibly better on the horizon but you'll always talk yourself into waiting and never have that state of the art system you want.
You go look at the Boinc stats page again from the link in the first post in this thread.
The numbers themselves should say it all to you.
Heck, there are dual socket 8 core Beckton system's there that I'm beating with this 12 core Westmere.
Granted they are at 2270mhz and I'm at 3458mhz but they are supposed to be a newer design??
Makes no sense to me.
Maybe I'll have to wait till one of them is released at a much higher speed.
Also Beckton is 45nm vs 32nm on the Westmere's
They should run hotter is my guess.
Single socket 6 core Gulftown or dual socket 12 core Westmere I think will put one heck of a smile on your face..
There is a lot more I could add here but not until after the chips release to retail.
No need to piss off the big boys if you get my drift..

As to what Apple will charge for a Mac Pro thats sort of irrelevant.
Apple charges for one system what I can build 3 or 4 for the same money.
Pretty cases and good marketing but pretty cases don't do the work, it's what's inside that counts and as to marketing, well,ahh..Answer this question:
Does it do you any good that the price you pay for a mac is so over the top that it's difficult to know how they justify it.
The key is that they don't justify the pricing and if it makes people feel good to know they are helping to keep Mr. Job's in the lifestyle to which he has become accustomed then your free to do so.
Yea, I don't like mac's in case anyone was in doubt.

*edited for profantiy - ErikaT

Now thats funny
I tend to write like I talk to someone in the room.
Yes, the day the NDA lifts I will have a review of the cpu's out on at least 2 sites..maybe more..

I believe this is part of the NDA?