The questions already been answered but I want to add this to the overall topic.
I specifically bought a Mac to develop iPhone applications. What this single task opened up is far beyond what I was expecting. To list a few things:
- I'm extremely impressed with the hardware. No hardware vendor competes with Mac's hardware from what I can tell.
- The OS is sweet. I can't list all of the details but the virtual desktops alone is wonderful. Check out the Wikipedia page: http://en.wikipedia.org/wiki/Mac_OS_X
- I run Windows Vista from VirtualBox and it works great.
- Objective-C -- A very nice programming language; I which I could use it more on windows.
All in all, I can literally get rid of all of my non-apple hardware and run Mac OS X and Vista from the Mac hardware and everything would be great.
My point is, the Mac is worth the price.
Buying a $999 Mac may not be such a bad idea...
And please note, running the Mac OS on a non apple computer is technically a license violation. I don't agree it should be, but it technically is.
UPDATE: You said that you want to see how it is done. You don't need a Mac (or the OS) assuming that you don't want to compile and run programs. Visit the iPhone Developer page at apple. You can get some free samples just by doing the basic free registration (don't sign up for the paid one).
From there, you should be able to download a few samples and look though the source code. You won't be able to view Interface Builder files, but this would at least give you some idea of the Objective-C code.
You can further gather more information online by going to websites like: