As I predicted (not a great feat of prognostication, really), JoCo has announced on Twitter that the surprise guest is, indeed, a John. No word as to whether the other will also, er, join us.
Sign Up for the Jonathan Coulton Mailing List!
We'll send you four free tracks to start,
we'll never give your address to others,
and we'll make sure you know about the latest
news and upcoming concerts.