This trick definitely works and doesn't involve heat or special tools...
Spray a bit of release oil onto the post, hopefully it will work it's way down there (best to leave for a while). Lie the frame on the floor, then get an old handlebar stem and clamp it to the seatpost (tight enough so it doesn't slip) then get hold of some tubing or a set of forks and slide the tube over the stems shaft. Once everything is tight you should be able to start working the the tube/forks back and forth until the post starts to move. You'll probably have to stand on the frame. Longer tubing = more leverage
. Once it starts to move, just keep working it back and forth or keep turning in one direction and it will work it's way out.
Give it a go - it always worked for me. If all else fails, there's heat...
