I'm trying to get this feature to work with no success so far.
Here's what I tried:
1) created updatePlugins.xml and placed in root-location of intranet-server
2) added intranet-server URL to the list of plugin hosts (with and w/o adding /updatePlugins.xml)
3) press "check now" in update dialog - should have updated the (manually copied) outdated version already installed, but no results
4) plugin manager does not show the plugin provided in my updatePlugins.xml
The documentation in the online help is rather sparse on this subject..