Domus, a site I enjoy, but visit only once in a while employs a similar, but I think more successful version of this strategy. Here, the text box is a similar color to the dominant color of the photograph, is more transparent, and overlays less of the photo.
As a design, I think it accomplishes the tasks Mr McManus specifies, but more successfully. Of course, from TNR's perspective, it has the defect of already being in use.
But just as continuing the design issues discussion a bit, I thought it might be of interest.