snail: The only reason to consider a Mac just for development (Linux has GCC anyway, get that), is because of CUDA, and Networking. On 10.6 (wait until 10.6 to get one, or else you'll have to buy the upgrade), XCode will probably be able to cannibalize the GPU for compiling. In addition, if you have other Macs on your network, XCode can access their CPUs to speed up compiling.
You probably want a PC with Linux, unless you actually need all that. There are great PC laptops, and PC =/= Windows, so Linux them. Besides, Linux eats a whole lot less in terms of RAM and CPU than current Windows XP/Vista and any OS X. (Windows 4.0 > * ). In addition, a Mac does not run every OS- You can't run anything older than Windows NT (No 98, 95, 2000, ME, no Godly 4.0). In addition, it doesn't really run Linux. I don't know why, but booting a Linux Live CD (with BootCamp) nets me a install that sits at a menu with trackpad and keyboard not working (at least on Ubuntu 8.04).
I may sound biased, since having more people get Macs will net Macs more VIRUSES and SPYWARE and TROJANS (In fact, you might be the person who tips the scales if you get one), so do me and yourself a Favor. Get a PC and load it with Linux.
@The-Revolution: Actually, no one needs anything other than Food, Air and Water. Of course, there's the possibility that he'll kill himself if he doesn't get one at that level of ram, so you can't say it. Provided, Apple doesn't support higher than 4GB- The Chipset and OS might, but not getting AppleCare help.
If anything, bringing in the laptop with more than 4GB for any issues will net you: "It's probably due to the unsupported amount of RAM" for a crack in the Trackpad.
In addition, MacBook Pros are where it's at- MacBooks are pieces of crap.