I just heard about this from another source and figured I'd search HN before posting myself. I'm surprised this has not gotten more attention.

One thing they mentioned in the podcast I was listening to, was that they've actually proven they can detect explosives in the air through the leaves of the plant too.

They were also talking about triangulating signals from several plants to find the location of a pollutant in ground water.

They also notes that the procedure or modifying these plants is just pushing water containing the nano-particles onto the leaves with a needle-less syringe. And you could basically go up to any plant in the wild and do this.