Smart Dusting a planet

I'm no expert and it may be a hotch potch idea from all the SF I have exposed myself to over the years, but I can't help feeling that using 'Smart Dust' to explore planets, as reported by the BBC, could be something that will come back to bite us sometime in the future.

No doubt the little beauties would be inert till activated, so we're not talking spaceship blows up during launch and releases active particles into the Earth's amtosphere, and I am sure that merely data collecting particles would not react adversely with anything here...but it's food for thought for someone like me - read overactive imagination and a prediliction for daydreaming.