Yesterday evening Apple sent out an update for the Developer Preview of Mac OS X 10.5 Leopard via Software Update.
The details of the update are very slim but sources suggest that the update fixes some very minor security issues and at the same time tests the Software Update utility.
Apple describes the update which is 46.4MB as:
This Software Update delivers improved reliability and compatibility for Mac OS X Leopard Developer Preview and is recommended for all users.
The build number post update is 9A241e.