"They all find out that you opened the mail and they get an invisible tracking number, so if you go to a store ... that number is reported to them and they can build that information into a database, " Catlett said.

CNN: Privacy groups ask FTC to close e-mail loophole

We continued to a backstage area where mail trucks shared space with production crews at banks of monitors tracking the party already under way, as well as Mr. Craig's progress.

WSJ: Setting Stages Fit for Bond

Audio Ads also enables advertisers to track when and where their ads ran soon after the fact, providing them with a faster and more accurate way of tracking their spots than the usual invoices they receive via snail mail.

FORBES

Those applications now include online payment, video, mapping, e-mail, social networking, search and soon, DoubleClick's behavior-tracking advertising data.

FORBES: Out-Gagging Google

If you've also received a tracking number, however, your device is likely to be in the mail.

ENGADGET

These weapons aren't for killing the enemy but for shadowing him--identifying terrorists, tracking their movements, eavesdropping on their phone calls and cracking their e-mail.

FORBES: Spotting Evil

Satellite tracking will be used to monitor the movements of a serial sex attacker, according to the Scottish Mail on Sunday .

BBC: What the Scottish Sunday papers say