It had to happen; sooner or later someone was bound to invent a tool that goes both ways.
It's the Kress 360 BPS BiPower rotary hammer, which is produced at Kress-elektrik's factory in Bisingen, Germany. The tool has a brushless motor and can be run from a 36-volt battery or an AC power cord (the European standard: 230v 50Hz). According to the specs, it produces 2.9 joules of hammering force, making it roughly equivalent to these cordless models from Makita and Hilti.
The videos at the bottom of this page were produced by the manufacturer. The first shows the BiPower rotary hammer being used with and without a cord. The second is promotional, but I'm showing it here because it's entertaining (and Einstein is in it, so watching it might make us smarter).