I guess this fits in the UNIX board.
Just updated my iMac 233 to Panther. All went smooth, except...
I lost my mySQL databases. I ended up re-installing and, luckily, I had backups of everything.
Apache v1.3.28 & PHP v4.32 pre-installed, just uncomment AddModule/LoadModule, AddType and you are up and running.
Great development box, I can already see the speed improvements. Plus, Expose (a new way to hide and view windows) will save a ton of time.
Best of luck to all. and make sure you backup before you install.