Thanks!
Indeed, the color of the eye and the lack of the horizontal black stripe behind the eye were what suggested to me that it wasn't a grey rat, but I had no idea juvenile black racers had this kind of coloration. It looked to me alot like the pattern I've seen on red rats in the past. I wasn't aware of the difference in the length of the tail, but now that you mention it I can see what you mean.
I'm sure it must be a Southern Racer, like the one in the photos. I'm in Jacksonville (Northeast) Florida, and I've seen them here before, but never a juvenile.
Unfortunately, the snake died last night. It looked to have some puncture wounds on the neck when I got it (from the looks of it, I imagine it was probably brought to the student by her cat), but it acted fine for a few days before turning up stiff this morning.
In any case, thanks for all of your help, I'm very glad to have found a nice herp forum.