"return to last result" button in middle of pan n,s,e,w buttons.

Just noticed this. Top left, in the middle of the arrow buttons.
Is this a sort of "Back" button ? Any way to program it ?
I implimented a sort of "back button" in my app (http://gmaps.evilc.com
- see the "history" links below the map) - could I maybe set the button
to go the the last item in this list ?