Not how I wanted to start my workday. I'd been concerned about how hot the computer had been running. This morning when I pulled the the MacBook out of my bag and placed it on my desk on campus, I could feel this little gap in the casing along the battery on the bottom.

Apple Tech Support was relatively painless, considering. I'm out of warranty on this and there are no official recalls open, but they offered to replace it free. For now, I just have to remember to put it to sleep before I unplug it. Could have been worse, I suppose. [Google search on "exploding laptop"]