I've added to gmpy.sf.net two binary packages of gmpy for Mac OS X 10.4, one for the Python 2.3.5 that comes with the system and one for Bob Ippolito's build of 2.4.1. They still need GMP to be previously installed (I'm told the one that comes with fink works; I installed my own from sources, from the GMP's site at swox.com), and they're .tar.gz packages requiring unpacking with tar xzf from the Terminal -- so, not very Mackish -- but they may still help if you don't want to install Apple's free and powerful XCode (which IS currently an 800+ MB download, after all) and still want to play with gmpy's functionality on your Mac's Python, I hope.
Let me know if there's interest in me eventually doing a better job of Mac packaging... while I have a hard time getting ahold of Windows machines, and particularly suitable development systems for them, I _am_ rather full of Macs (& dev systems for them;-)... Alex -- http://mail.python.org/mailman/listinfo/python-list