Via @SAI
This AP article by Stephen Braun, Anne Flaherty, Jack Gillum, and Matt Apuzo, seems to be the most reasonable and seemingly responsible report on PRISM that I’ve seen yet. It seems to be pretty much in line with my own limited understanding of what the relevant government agencies actually do, based on public information.
Image credit: Mr. T in DC on Flickr. CC BY-ND 2.0.