Query: For the first time, recordings of the contestant's songs could be purchased where?
Context: Jason Castro's semi-final performance of "Hallelujah" also received considerable attention, and it propelled Jeff Buckley's version of the song to the top of the Billboard digital song chart. This was the first season in which contestants' recordings were released onto iTunes after their performances, and although sales information was not released so as not to prejudice the contest, leaked information indicated that contestants' songs frequently reached the top of iTunes sales charts.