... but, yeah, the info-beam-back-to-Earth bit is missing.
Plus, I've just finished reading The Dark Forest and we should not in any way indicate where the probe came from - evasive maneuvers are mandatory. Oh, wait...
Looks like a neat idea however. Couldn't we use it to fire stuff at targets within the Solar System? As long as we kept the speed down quite a bit, made do with quick flybys and actually sorted out the call home bit?