In December 2005 I wrote without having proof:

Thesis: The U.S. administration is using an automated communication surveillance system to monitor communications between the domestic U.S. and foreign countries.
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The system listens to and processes communication in realtime. It is preconfigured with specific phone numbers, email addresses and/or keywords.
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Database mining technologies and automated statistic methods are used to find patterns within and between the recorded communications. The discovery of such patterns may lead to further investigation or may modify the system’s sensitivities.

The WSJ now confirms all the above. But there is even more of domestic spying involved than I assumed:

According to current and former intelligence officials, the spy agency now monitors huge volumes of records of domestic emails and Internet searches as well as bank transfers, credit-card transactions, travel and telephone records. The NSA receives this so-called "transactional" data from other agencies or private companies, and its sophisticated software programs analyze the various transactions for suspicious patterns.

This is essentially a new and wider implementation of the ‘Total Information Awareness’ that was killed by Congress.
Like I described before, the system picks a lead and extends from there, eventuall catching all available traffic.

Two former officials familiar with the data-sifting efforts said they work by starting with some sort of lead, like a phone number or Internet address. In partnership with the FBI, the systems then can track all domestic and foreign transactions of people associated with that item — and then the people who associated with them, and so on, casting a gradually wider net. An intelligence official described more of a rapid-response effect: If a person suspected of terrorist connections is believed to be in a U.S. city — for instance, Detroit, a community with a high concentration of Muslim Americans — the government’s spy systems may be directed to collect and analyze all electronic communications into and out of the city.

The haul can include records of phone calls, email headers and destinations, data on financial transactions and records of Internet browsing. The system also would collect information about other people, including those in the U.S., who communicated with people in Detroit.

The information doesn’t generally include the contents of conversations or emails. But it can give such transactional information as a cellphone’s location, whom a person is calling, and what Web sites he or she is visiting. For an email, the data haul can include the identities of the sender and recipient and the subject line, but not the content of the message.

If you believe the last half sentence, you have just won the chance to buy that proverbial bridge in Brooklyn.

I still believe, as I argued before, that such systems are useless for catching terrorists, as they generate too many false positives. But such a system is very useful if the people with access to it want to get information on specific ‘persons of interest’ – journalists, opposition politicians etc.

If you have wondered about some democratic votes in Congress that supported Bush issues despite their own interest and about a lack of press scrutiny into administration abuses, the answer is right there.