The article talks a lot about their rectifier and im guessing that's where the 'breakthrough' is, but still I feel this is like too many of these articles where its a lot of hype for a little progress.
This is also how passive RFID tags work, the tag harvests just enough energy from the scanning frequency to boot up a microchip and respond with its ID number.
It's almost certainly going to be milliamps or microamps unless you're inches from something. This isn't for cellphones and the like but for remote sensors and the like. I also bet they'll at least have to have a capacitor to store up extra charge for chirping back only sometimes.