I’ve just finished updating my test server with Mac OSX 10.5.6. Both updates went without any problem and my setup was not affected in a negative way. Only had to get a new version of GPGmail. Every item had started after the reboot and worked according to expectations.
In case of doubt, please make a full bootable disk image backup with Cabon Copy Cloner before you start.
I will update my production machines this weekend when I’ve got some more spare time. If you want to be sure everything is allright please wait untill then.
Update: There was an issue with postfix, please read the update