The Department of Defense is pursuing a brain-implantable "biochip" that will measure/relay a soldier's vitals on the battlefield (and off). We don't know much from a technical standpoint about the chips, other than they are about the size of a grain of rice and will have the ability to, at minimum, measure oxygen levels in tissue. But the technological breakthrough involved has little to do with the electronics.
Scientists have invented a gel that mimics human tissue. By combining the gel with the microchip, chances that the body will reject the device are far less likely. The entire project is said to be five years from implementation.
Personally, I'd love to see these microchips developed for civilian use, especially for diabetics and those who need constant blood work. But when framed as a government, military initiative, the altruistic potential can be scared off by Big Brother. [intelligencedaily via inquirer]