Swedish website sweclockers got some reliable information about Intel's new generation of CPU, Ivy Bridge, which will be in the 2012 models of our Macs.
In the next few weeks, Intel will ship the first prototypes so they can be tested but we will have to wait for April or even March 2012 before they start shipping to the general public, and they will be only the quad-core models first, as the dual-core ones will have to wait a few extra weeks.
This delay between the launch of the two versions will be longer than usual and it could be a problem for some manufacturers, including Apple. if we put this new rumor alongside the one about a 15" MacBook Air/Pro, we could see Apple using one if its usual strategies to revamp the sales without changing a lot inside, the change in external design.
Apple did it in October 2008 with the launch of the Unibody laptops. It was the principal evolution, while the internal specs remained unchanged and even went down on the MacBook since the CPU was slower than previous models and it was at that time that it lost its Firewire connection.
It will probably depend on the sales numbers and some other internal factors. Changing the manufacturing process of computers is a lot harder when it is not made of plastic but carved aluminum, especially when you make millions of them. It was with that very same unibody manufacturing process that Apple had a very hard time reaching a high production rate in late 2008.
For the iMac it will be hard to see another evolution in the design since in the last few years Apple tried to make it more and more simple. It has become more and more screen and less and less computer, so it can't be a lot thinner than what it is now, but Apple could choose to make the display even bigger… and hopefully without dust spots!
We will have more info in a few months. If there is a radical change in the design, it will be this Fall or early Winter so the models can sell for about 6 months before the switch to Ivy-Bridge CPUs.