The Bush administration has invoked state secrets several times recently, on two sets of issues: telephone data searches and on what's known as extraordinary rendition, the transfer of terrorism suspects to third countries.

NPR: Invoking the State Secrets Privilege

In both cases, several unrelated types of calculation, using independent data sets, and running on a range of computers in different organisations that may not fully trust one another, have to be threaded together to achieve a coherent answer.

ECONOMIST: REPORT: COMPUTER NETWORKS: Computing power on tap | The