Public Radio Player Version 2.1, an upgrade of the iPhone app developed by Public Radio Exchange last year, is now available for downloads in the iTunes App Store. PRX rewrote the code to improve the app’s performance and added features such as a sleep timer, alarm clock and the ability to bookmark your favorite listening selections. There’s something else very different about the latest player: PRX is introducing national banner ads on top-level pages. “CPB has encouraged us to find ways to sustain the project beyond grant support so this is our first foray into mobile advertising,” explains Executive Director Jake Shapiro on PRX.org. “We are working to make it possible for stations to sell local ads on their own Player pages.” A broader roll-out of local station ads is planned for version 3.0, which PRX will release in June. CPB recently renewed its funding of the Public Radio Player, a pubradio collaborative project that PRX has managed since 2008. The first version offered live streams of 150 public radio stations. Now 500 are accessible through the app.