It turns out that there was some debris that fell off of the external fuel tank during separation (when the orbiter was somewhere around 60 miles above Earth). The debris fall-off was picked up by one of the cameras on the external tank, and did not appear to contact the orbiter.
There was also a bit of debris that seemed to fall off near the tiles at the front landing gear. It is (right now) believed that this was a bit of tile from the front landing gear area, one of the hottest parts of the shuttle upon re-entry.
NASA engineers and administrators will be examining and analyzing the camera footage in the next few days, to try to determine the extent of the damage. For all they know RIGHT NOW, since we have never seen this part of a mission before (prior to this, the cameras were not in place), this could be "normal" damage that always occurs. The examination of the orbiter by the shuttle remote manipulator arm, by the astronauts on EVA (extra-vehicular activity), and by cameras and CanadArm2 on ISS will also help evaluate the extent of the damage, in addition to the ground-based evaluation of the shots captured during today's launch.
Well, we've got them up there. Now we need to get them home. Oddly enough, I haven't seen anything about this debris on NASA's website (at least, not in a quick scan), though both the BBC and CBS News have a (very little) bit on it. Seeing as I've got nothing better to do in general these days, I'll be following the mission and its key aspects, and post anything interesting up here.