Arbitron reports that its Portable People Meter (PPM) system is capable of tracking podcast audiences (via AdJab). During the week of July 18, Arbitron encoded several podcasts by Clear Channel's Z100 New York that were uploaded to the podcast portion of Apple's iTunes Music Store. The podcasts were then downloaded to an MP3 player and played over headsets using the PPM headset adapter. The PPM detected and recorded the unique identification codes that were embedded in the MP3 file.