Apple - What does "plays" really count in iTunes?

I believe that you just have to listen to the last few seconds of a song. You can skip all of the beginning part, and it will increment the Plays if you listen to the end.

In the behavior I have seen in the 5+ years of podcast listening. iTunes marks it as played based on a percentage listened. My guess is that would be about 98-99% listened. A 5 minute show would basically be the end. An hour and a half show would be just the last few seconds.

In case Nathan G's answer wasn't super-clear: play count == number of times the file played right to the very end. That means you need to let an audio file play right to completion - either until the next track starts to play, or you are returned back to the song list (if it is the last track in the list).