The Blog feature has built in support for the Google Plus button, but under the hood it is just using a new control in mojoPortal content management system. You can add this same control to the layout.master file of your skin to have a google plus button on every page that uses that skin.
Shown here with all the default values:
<portal:PlusOneButton ID="btnPlusOne1" runat="server"
Leave TargetUrl blank to make it use the url of the current page.
Valid Options for WidgetSize are small, medium, standard, tall
Created 2011-08-04 by Joe Audette