Pandora has 60m active users

"US streaming and discovery service Pandora now has 60m active users.
The company announced the figure at the New Music seminar in New York. In April, it has 50m users, up from 40m users in December 2009.
Key to the company’s growth has been the development of apps for all the major mobile platforms. The company’s founder Tim Westergren revealed last year that over half of new users were coming to Pandora via mobile.
Pandora also added that of the 90,000 different artists on the service, 80% are played at least once a month.
Last year, it generated $50m (£33m) in revenues and paid out $30m (£19.7m) in royalties."
Source:  Music Week, 22nd July 2010