There was a M7.5 in northern Sumatra...vaguely near the south end of the Dec 2004 great quake and near the north end of the March 2005 great quake. The USGS site does not have a focal mechanism up yet, but it is liable to be thrust, because the epicenter is near the subduction zone. It will be interesting to compare this quake to slip distributions for the 2004 and 2005 quakes: is this filling in an area that had small slip or that did not slip, is it on some fault above the subduction interface (above the megathrust), or did the same part of the same fault that slipped before slip again. I won't know the answers to this unless someone posts it or until something comes out in print that I happen to see.
Chris