From a Wired report by Tim Maly at Wired a microchip by Freescale that is so small that, yes, it can be swallowed:

“Chipmaker Freescale Semiconductor has created the world’s smallest ARM-powered chip, designed to push the world of connected devices into surprising places.

Announced today, the Kinetis KL02 measures just 1.9 by 2 millimeters. It’s a full microcontroller unit (MCU), meaning the chip sports a processor, RAM, ROM, clock and I/O control unit — everything a body needs to be a basic tiny computer.

The KL02 has 32k of flash memory, 4k of RAM, a 32 bit processor, and peripherals like a 12-bit analog to digital converter and a low-power UART built into the chip. By including these extra parts, device makers can shrink down their designs, resulting in tiny boards in tiny devices.

How tiny? One application that Freescale says the chips could be used for is swallowable computers. Yes, you read that right. ‘We are working with our customers and partners on providing technology for their products that can be swallowed but we can’t really comment on unannounced products,’ says Steve Tateosian, global product marketing manager.”