I ordered the 27″ i7 quad core 2.8GHz iMac last week. It still hasn’t shipped – the order status still says “Ships: November”. A lot of people who ordered them earlier are starting to receive them, and from early reports, the performance is outstanding.
For the last few years, I’ve been using laptops with 15″ or smaller screens & speeds of 2.5 GHz or less exclusively, so this will be a nice upgrade. I’m really starting to feel the limitations of the MacBook Pro when running a Windows 7 VM and trying to do useful work like XCode builds in OS X with 4GB of RAM.
I’ll be keeping only the 13″ MacBook, since I prefer it to the 15″ for traveling.