I came across these two new images, both from AP, of the Beichuan area.
The first shows the landslide that struck Beichuan itself. The landslide is on the left side of the image. Note the debris piled up around its edges - the landslide has clearly bulldozed all before it.
The second is an alarming image of the work underway on the Tangjiashan landslide dam. The shear scale of the blockage is clear. Of great concern here though is the steepness of the slope. Controlling water flow in a channel on slopes like this will be immensely difficult. The potential of scouring out of the channel, and thus of rapid collapse, is worrying. Looking on the bright side, seepage shouldn't be an imminent problem.