Yes Geeklog updates handle by a plugin would be a very nice feature

and
multi plugin should have this feature... if we want to upgrade at once all sites created.
Todo list:
- Record each db site infos (name, user, pass) to allow changes config (global or not)
- Unable/Disable a site
- Delete a site
- Global upgrades (core, plugins)
I'm available to customise your themes or plugins for your Geeklog CMS