>>http://www.bbc.co.uk/news/technology-22905199
>
>That's an idea that's been explored for some time e.g. http://en.wikipedia.org/wiki/Stratellite , but Google's looks like the first stab at it by a company with serious financial clout.

That, on the face of it, sounds like a more sophisticated approach. Powered to mainstain a stable position and with a much wider footprint.

As the article states, I can't see how the Google version will even be able to reliably dictate the course. If the only option you have is changing altitude to select the best wind direction you'd still be limited to, say at most, 20-30 degrees. And although it is easy to cause a balloon to descend I'm not sure how they intend to cause an ascent - you have to re-inflate the balloon somehow which implies carrying reserves of gas. And with only a 20km reception radius you'd need an awful lot of them to provide continual coverage.