Woops. It looks like Apple might have made those new iMacs a little too fast!
The Core i7 iMac beat the Octo-core Mac Pro 2.26GHz in a number of Speedmark 6 tests and overall it was 1.5% faster than the fastest base model computer Apple sells. Sure, you can update that Mac Pro Beast to 2.93GHz Octo, but that is £1700 more, £325 more than the entire Core i7 iMac! Even the Core i5 iMac did pretty well. Oh, and that iMac has the best display Apple has ever produced.
Our tests of the built-to-order Core i7 iMac (which, other than the processor, has identical specifications as the stock Core i5 iMac) showed even greater performance prowess. With a Speedmark 6 score of 225, the Core i7 iMac was nearly 8 percent faster than the Core i5 iMac. The Core i7 was nearly 11 percent faster than the 2.66GHz Quad-Core Mac Pro and 9 percent faster than the 2.26GHz 8-Core Mac Pro. In our tests, there were a few tasks where having eight physical processing cores was beneficial, like our MathematicaMark and Cinebench CPU tests.
Sure, these are just a few specific tests and users real-world mileage will vary. But it does show that the fastest iMac can hang around with the Mac Pros. In fact, unless you need to add internal RAID hard drives and/or extra PCI cards (or hate the hi-shine™ display), it is hard to imagine many cases where the Mac Pro workstation makes more sense than the cheaper, faster iMac Core i7 that also includes the best display Apple has ever produced!