New iMac in different colors?

Not likely. Apple's current designs based on a brushed metal concept. Apparently we can't have it all.

If you really want to have a colored mac and don't mind paying for it I found a place for you that has a great reputation for "pimping" Macbooks. Here's what they say:

If Apple's black and white designs are a little too bland for you, consider letting the paint pros at Colorware spray your new MacBook in a nice shade of red, purple, green or pretty much any other color you can imagine. After recently seeing their work in person, there's simply no other company we'd ever recommend to do something like this. With Colorware's MacBook custom paint service ($450) you can pick between 28 standard colors — or you can pay $100 more to have them mix you a custom color. You can even send in an Apple Mighty Mouse or an extra battery ($20 each) to have painted to match your fresh new MacBook.

http://www.uncrate.com/men/gear/laptops/pimp-your-macbook/ 

Hope this helps until Steve Jobs decides to release colored Macbooks!