One comment made me realize I should have been clearer. I definitely think the Forrester data is right; as growth in new ipod users slows, iTunes sales are dropping off and will continue to do so. Apple will get a big burst of sales this holiday as the new millions of users come onboard, and will have a nice announcement next week, but unless they generate long term sustained buying from existing users, it's bound to drop off.

That said, it's not a problem for Apple and doesn't mean Apple or Itunes are in trouble. It just shows that users aren't switching to itunes as their main way of obtaining music.