Wired's David Becker today picks up on Pink Tentacle's report that Hitachi has introduced a prototype RFID chip measuring 0.05 millimeters square and 5 microns thick -- about the size of a grain of sand.

"Conspiracy-minded types can thank Hitachi for something new to worry about -- RFID chips so small you'll never know they're there," Becker writes.

The chips, which Hitachi says will be on the market within the next three years, will hold 128 bits of static memory. The chips will be perfect for embedding in paper to validate, say, checks or cash.

"Beyond that, let your fevered imagination wander," Becker writes. "We, for example, are reminded of the mysterious Dust that pervades Philip Pullman's His Dark Materials novels..."

More here from Gizmodo ... and more here from Technovelgy.