pawn end game

http://www.chess.com/echess/game.html?id=46211737#

again, I am struck by the complexity of simple pawn end games. I entered lightly into one with one pawn plus (in move number 40) for white and now I am sweating over the possibilities. As I am writing this I am finishing up the game, outcome to me right now absolutely unclear. Please do not post any analysis here but feel free to have a look.