Hannibal over at Ars has written two good articles on the NSA wiretap scandal. First he goes into what can be gathered by reading quotes of people who know about the program. He also talks about what has been previously mentioned about this technology. In the second article he neatly presents an easy to read summary of why mass surveillance is bad. If you read anything at all about this issue read these articles.
The new technology at the root of the NSA wiretap scandal
NSA wiretap followup: Why computer-automated mass surveillance is a bad idea
Update: Bruce Schneier has a very good post about The Security Threat of Unchecked Presidential Power