How thin are RFID chips getting these days? Thinner than the Zune’s chances of overtaking the iPod in the DAP standings. The latest and thinnest of the RFID bunch comes to us again from Hitachi, makers of the Mu-chip. Mu’s newer cousin doesn’t have a name but does have a thickness: 0.002 inches by 0.002 inches—in other words, the thickness of a piece of paper.

These chips look like tiny bits of powder yet can handle the same amount of data as a Mu-chip, which is 60 times larger. What these chips don’t have is an external antenna, which by itself would be much larger than the chips whose signals they would broadcast.

Mu-chips are so small that they border on being invisible, yet Hitachi says it has no plans to mass market and sell them to commerce mavens to track their products, or to government agencies for tracking citizens’ movements, willing or otherwise.