About this plugin
Many plugins support google authorship integration (less offer google avatar but this is kind of minor feature) so why create another one?
The trick of this plugin is to eliminate the need for copy & pasting the user profile URL\’s, by using the google API to retrieve the required data for the user. An already registered application is used as a proxy for authentication and using the API, and no extra work is involved. For the user, authentication, and gathering the required info, is just one click away from their profile page.
Please read the installation instructions, there is more there then the trivial instructions
Network use
The plugin will work for any sub site in the network for which it was activated (or if the plugin is network activated).
Any change the user will make to its profile will impact all the sites in the netwrok in which the user had posted or commented.
Limitations
Only the user can authenticate himself, therefor an admin can not set authorship or avatar instead of the user.