This was another bit of good karma that came as a result of the spare hens'n'chicks I passed out. Nice Friend has been rooting it for weeks, and finally deemed it ready for potting. She tells me it's called a "Wandering Jew". With a name like that I knew it had to have a story.
Of course, wikipedia reveals all. Here's the info on the plant--which is properly called Tradescantia zebrina, by the way--and here's the story behind the name. Apparently you can make tea with it's leaves as well.