I switched from Linux to Mac in 2003. I had a laptop stolen, and really liked the idea of a slick PowerPC laptop running Unix. I figured if I didn't like OS X, there were several PPC linux distributions I could choose from. It turns out, I liked Unix, and OS X served my needs better than Linux (all of the Unix utils plus significant commercial application support. Three more Macs later, I don't even think about it when buying a laptop.
I've seen fink mentioned above, but I prefer MacPorts.
Its great to see where things have come in the last few years.
I didn't switch from Linux to the Mac but I did buy a mac(book pro 17") because I got sick of my Linux laptop not being able to connect to encrypted wifi and having suspend/restore break randomly.
I do about 70% development on Linux and the rest on the Mac. I'm really happy with my Mac now, but it did take a long time to get used to it. Particularly getting the keyboard to work reasonably similar to Linux so I didn't have to totally retrain my fingers for Emacs, and getting GUI Emacs (Carbon) to use the same keymappings as Emacs in the terminal. (Doublekey helps with that.) Other things that are still irritating are the impossibility of focus-follows-mouse and the single menu bar at the top of the screen.
Anyway, I'm really happy with the Mac now and it's great how nice things like fonts, functioning accelerated video drivers, and general work-out-of-the-box-ness are. I'd definitely buy another.
