48 hours later, and it's time for a progress report. There's a line across the middle which isn't burnt, corresponding with the location of a crease in the t-shirt during the incident. The whole thing is about two and a half inches across.
Click for a bigger one.
It doesn't look like there will be a permanent scar.
Edit: In response to a helpful comment I've received elsewhere -- the thing you can see in the corner of the picture? It's my navel. My navel. Thank you.