It looks to me like one of the many "blue" tomatoes that are now showing up, first developed at Oregon State University and also in England (although the latter supposedly more GMO than the former.) It seems to have the same characteristics, turning dark (call it blue or black) according to the sun exposure, containing anthocyanin (the blue pigment) from the "wild" tomatoes, etc. So far the ones I've tasted have been very bland but I hear if left much much longer on the vine they'll tend to gain better flavor.
Linda Sapp, owner of Tomato Growers Supply has now included seeds of a blue tomato in her menu of varieties if ya'll would like to start there.
Shoe
