NSA domestic spying -- What's really going on?

Kevin Drum is probably on to something. Some new technology is probably at work in the NSA domestic spying scandal, one that must be awfully intrusive.

UPDATE: Lots of people have suggested that the NSA program has something to do with Echelon, a massive project that vacuums up communications of all kinds from all over the globe. The problem is that Echelon has been around for a long time and no one has ever complained about it before — so whatever this new program is, it's something more than vanilla Echelon. What's more, it's something disturbing enough that a few weeks after 9/11 the administration apparently felt that even Republicans in Congress wouldn't approve of it. What kind of program is so intrusive that even Republicans, even with 9/11 still freshly in mind, wouldn't have supported it?