Now I've been home, so I'll update.
The snake is actually very pretty. Her name is Victoria, and while she is about three feet long, she's not nearly as fat as I thought - only about an inch and a half at the most. I haven't had her out of the aquarium/habitat yet, because I think they need a day or two to settle down after being moved. Apparently the coworker (whom we'll call "Kurt," since that's his name) has been feeding her live rodents - I told DH he needs to let Kurt know that Vicky's feeding habits are going to change. He also needs to get a thermometer and a humidity gauge, because if I'm gonna do this, it's going to get done right.
She barely moved all day. There's a tree branch in the cage, and she spent the whole day coiled up in the fork of it. I know she can move, though, 'cause I left the room and came back a few minutes later to find her entirely on the floor of the habitat, then back up in the tree again in the time it took to pour a glass of V-8.