From the BBC, First human ‘infected with computer virus’-

Dr Mark Gasson from the University of Reading contaminated a computer chip which was then inserted into his hand.

The device, which enables him to pass through security doors and activate his mobile phone, is a sophisticated version of ID chips used to tag pets.

In trials, Dr Gasson showed that the chip was able to pass on the computer virus to external control systems.

If other implanted chips had then connected to the system they too would have been corrupted, he said.

Here’s a situational example of how this could be used maliciously.

-Pentagon contractor comes in for a hit replacement or other large, invasive procedure. Broadcast device is implanted as part of the procedure. Person returns to work, and the device gains access to secure networks. Device can be set to retrieve data then broadcast once the person comes home to an unsecured network.

I’m not saying this can happen today, but a few years from now I could completely see this being the new method for espionage.