Even though I’ve had Leopard installed months ago, I just grew comfortable having all the apps and drivers I needed on my 10.4 machine. It wasn’t until this weekend where I took the leap to get things working.
Its been blogged quite extensively and was pretty straightforward (except for needing to use MacPorts to install gettext before being able to install vorbis-tools, then FLAC. I used MacPorts to download mySQL5 (as there wasn’t a PPC 64bit version available) – you have to get the 10.5 version of MacPorts (not available on the home page)
There are a few things you need to go through to get MySQL5 running with apache2. Once you’re up don’t forget to change your socks (its all talked bout in the links)
The biggest stumbling block was getting Port based Virtual Hosts functioning, and after scouring the same responses, I found the answer. I know a little more about apache now 
So hopefully if you’re doing the same then take a look at these links.
http://suburbia.org.uk/blog/2007/11/13/120206.html
http://alexking.org/blog/2007/11/01/apache-2-only-serves-first-virtual-host
http://mymacinations.com/2007/10/28/apache-php-and-mysql-on-leopard/
There
are a bunch more, but these will help you get started and should shave
hours off your frustration. Oh and as PEAR is not functioning out of
the box from Apple either, you have to install PEAR too (if you use it,
i do):
Working-with-php-5-in-mac-os-x-105/
I’d review all the links first and then take your course of action, it will save you lots of time !
Ket