Found an interesting tidbit over at Slashdot about Microsoft patenting a system to detect user frustration. The system uses biometric data (along with interaction statistics like time to complete task) to determine if the user is frustrated. If they are, it can connect them with help in the form of support or someone else completing the same task.
While this is somewhat interesting from an HCI perspective, here's a more interesting idea: Design products that don't require you to monitor user frustration levels. Just a thought...