I’ve updated my test server with Mac OSX 10.6.1 The update went without any problem and my setup was not affected in a negative way. It took me some time to check everything.
If you want to read more on what is affected in the updates I would suggest reading the Apple support site for the 10.6.1 update.
In case of doubt, please make a full bootable disk image backup with Carbon Copy Cloner before you start. There are some people having reported problems with previous update so better be safe then sorry!