For those of you who are anxiously awaiting an update of the iMac, I have a different question: why? What does it do for you that a MacBook Pro and a display would do for you?
Unless there is something I am missing here, I cannot imagine buying another iMac.
This is one silly question!!
As others have stated...PRICE!
In the UK a 15" MBP + Apple TBD is £2700. You need this spec MBP to get the speedier processor and dedicated graphics card, 8GB RAM etc.
Base spec iMac (no doubt the next gen will match the latest MBP spec) is £1400.
That's pretty much HALF the price, for the same processing power. Not to mention a larger HD.
For business it's an absolute no brainer. We run a design consultancy. We have a few MBP's MBA and iPads, don't need Mac Pro's, so an iMac is the perfect fit.