My Time Machine backup is AFP based network share that is located at my office LAN, but regardless of my location, Time Machine tries to access this share and when it can, it starts backing up. This might not be that bad idea, but my home network upload is not that good, which results in waste of time and bandwith as TM never completes even the first step of calculating differences.
So, first I sought out for solution to disable access to AFP volume from the world, which would cut me off the whole volume, though. But then I stumbled upon this post, which in essential shows how to toggle Time Machine from command line. Combine this with Marco Polo and you get yourself a Location Aware Time Machine.