Apple today released Server Admin Tools 10.5.6, which enables remote administration of Mac OS X 10.5.6 Server. Full details on the package contents can be found on Apple's download page and on their corresponding support page.
Server Admin Tools 10.5.6 contain remote administration tools, documentation, and utilities that you can install on a computer other than your server. This version is required to administer Mac OS X Server version 10.5.6 from a remote Mac client.
The package weighs in at 88 MB and requires OS X 10.5.6.