Once you have configured the Server app it will download and install its components which are not deleted with the app.
Server app is just an interface to these individual control modules similar to command line tools or like preferences items that plug into the server.app
You can use the above method to look for the files that the server.app downloaded but I doubt if you can straightaway delete them.
The Server.app once configured will mark your OS X Lion as OS X Lion Server and you will continue to receive server related update alerts even if you delete it.
This file is created when you configure the server and OS X Lion will look for it while checking for the software updates.
If you delete this file OS will fallback to "SystemVersion.plist" in the same folder and your machine should be back to non server updates :)