If you're a WordPress developer and have been looking for a good guide on setting up a local installation to do some testing, you might want to check into this guide from NETTUTS.com.
If you're a heavy WordPress developer like me, you might find that you need to create a new installation for each site that requires a strange structure or specific posts, instead of using your uniform local test WordPress installation. Cue WordPress Mu. WordPress Multi User is a platform created by the geniuses at Automattic that is basically a WordPress installation that allows multiple blogs to run using the same software.
The tutorial requires you to already have a setup install of WordPress on your local machine and a working MAMP setup. The guide shows you how to change ports in the config, update the httpd.conf file for the webserver, add in a virtual host and configure the hosts file to point to your WordPress MU installation.