The Arrange: Align commands are great, although I'm still experimenting with how they work with tab guides. Can you add an Arrange: Distribute (evenly) command set as well?
This is how the 'arrange' and tabs works at the present time. First, turn on the Guide Border (icon on the top tool bar). Now, if there are no tabs, then an object will move relative to the guide borders. If you have multiple objects and create a temporary group, each object will move independently when you click one of the arrange buttons.
Now, if you put a tabstop on the page, then the arrange will move relative to that. Furthermore, if you place an object over a tabstop, then pressing 'center' will use the center of the object as the reference point.
I think 'Distribute evenly' was brought up once before. I'll check.