The royalty rate that Pandora pays will increase 10% a year until 2015, which is when their current agreement expires. So, essentially, they have to be 10% better at extracting value out of each song played over the next 3.5 years. All bets are off come 2015.

http://techcrunch.com/2010/06/16/tc-teardown-pandora-the-tou...