I noticed an interesting little feature in the help menu. A search is now integrated directly into the menu. I’m sure this will be nice for those people who RTFM. 
This seems to be present in every application.
I have been spending the evening looking at my fresh install of Leopard (Mac OS X 10.5). It looks like PHP version 5.2.4 is installed by default. As of today, this is the latest version available. So far, the built in web server is not processing .php pages. I’ll look into that next.
UPDATE: Upgrading to 10.5.1 has resolved the issues displaying PHP pages.