BusinessWeek is running a story about how the US Government is buying public databases that contain all manner of information about people, including their financial information and biographical information, all often tied to your phone number.
Having the ability to combine that information with the illegally obtained phone calling records and who knows what else being collected gives the government a lot of information that can be used to harass people, or worse yet tie them to crimes they didn't necessarily commit. I've stated it before, it only takes one call to someone who's doing something shady to have your name in a collection of "suspects".
Consider me, for example. I have worked in companies that include people from India. Now say one of those persons is a Kashmiri muslim ( I have twice worked with Muslims from Kashmir ) who through a friend is connected to a known terrorist in that area (that part is I hope made up).
His friend calls him from Kashmir to talk about his upcoming trip back home. He then calls me for a few minutes to talk about something relating to work or cricket, whatever. I'm only 4 steps removed from a terrorist. Doesn't mean I'm a terrorist, but I'm flagged. The FBI then does a search of my purchasing records and finds out that not only have I bought two books on Learning Hindi but I've also bought the Koran, and searched on Amazon for books about learning Pashto and Urdu (languages in Afghanistan and Pakistan). They have no way of knowing that I did so when I was entertaining the idea of working as an open-source translator for the CIA or NSA. I have now become a "person of interest". Suddenly my calls are being listened in on, my email is being filtered, my whole life, and the lives of the people around me are being analyzed. The fact that I have a PGP key and employ it is viewed as highly suspect. The nature of the writings I have posted on this blog and elsewhere are held up as evidence of some greater plot or sedition. My friend Jeff is flagged as being associated with a "person of interest" and comes under scrutiny by his military commanders. Both of my brother-in-law's jobs become jeopardized. My mom's private phone calls as a pastor are listened in on. The circle of inquiry widens further and further. And all because I could be four links away from a known terrorist.
Think that's crazy? Bush himself is one link away from Osama bin Laden himself. The Bush family knows the bin Laden family well. So consider for a second how you may be connected to a "person of interest" even if only tangentially. Do you want the government snooping through your life on such flimsy evidence?

Great post. Sensible rationale. Prudent warning.
Too bad only you and I are listening ;-)
I've said it once, and I'll say it again. "They" can listen in to my phone calls all they want..."they" can dig all they want. All they're going to get from me is a whole lotta nothing, well maybe other than an interesting conversation or two between me and my girlfriend, but that's fine, that MIGHT give the stiffs at NSA a hardon, and that's it. Really, if it prevents another 9/11 (or worse), and if it saves even 1 innocent life, then so be it, and I think it's worth it. Having been in the military for going on 7 years now, I'm used to having my rights curtailed and infringed, and see no reason why other people shouldn't have to do it, as well, all in the name of combatting terrorism. That is the world we live in now, like it or not. Really, if you, or anyone else, has nothing to hide, what is the problem? I just cannot see what the big deal is, and why people care, if it is going towards protecting and saving the lives of our citizens. But then again, I took an oath to do that, and that part of my military service, I happen to take very seriously.