Another one of my conspiracy posts: former FBI counterrorism agent Tim Clemente saying the "all digital communications are recorded and stored" and "no digital communication is secure" (he was trying to convince everyone that the government had the Boston Bombing investigation under control)
Video of Shia Labeouf saying that an FBI consultant played a recording of one of his phone calls from 2 years prior to working on a film in 2008: http://www.youtube.com/watch?v=3ux1hpLvqMw
And here we are 7 years after one of his voice calls was recorded.
It's not just metadata, they collect full audio & text content as well. http://en.wikipedia.org/wiki/Room_641A