What year should the Mac Mini be for apps programming?

I am trying to learn objective-c to start programming apps for iphone. I have read alot of forums and people recommend the Mac Mini or the Imac. But the Mac Mini should have at least 4gb of ram. Somewhere I read for the Mac Mini to be 2006 or newer. Why? What about the Imac, what year should that be?

Mac Mini best answer:

Answer by Shawn B
So that you can have the Intel processor. No sense in programming for an obsolete processor. Also, you probably want to be able to upgrade to the latest OSX, which requires the Intel processor.

Edit: I should mention… just for fun I made my own mac. I added a hard disk to my Window 7 computer. Now i can multi-boot the same computer into either Windows, Snow Leopard, or Linux. All I bought was the Snow Leopard box set, and followed “hackintosh” instructions from the internet. It was really hard to do though, and took me three solid days (my entire weekend) to get it working. I would rather have a mac mini, but can’t afford it.