Thats cool, this could be really interesting if they can make it work. Was thinking to myself that this would likely end up being prohibitively expensive for anyone using the internet, but if one balloon can cover 40 sq KM thats pretty good, if you could get 20-40+ people paying out 40-50$ or something, it could do ok.
It might not be super profitable for Google but it would be a great way to test new technology and ideas and expand Google's presence in the world, good PR.

I'm no meteorologist, but since these are not tethered, it would seem you'd have to launch a new balloon every day to account for drift. Will there be people at sea gathering up the old ones? Good idea, particularly after a disaster when the grid's down, but long term makes me wonder if they're worth the cost.

I would be interested to know how many connections can be handled at any one time, and at what point this would start significantly affecting the speed.

Something has gone terribly wrong somewhere Google searches are not working as well as they use to, and now this.

heheh - would this be new cloud-based infrastructure?

Hope this works. If it does, then maybe ships at sea could offer affordable internet access.

Now that solar powered airplanes have been created that can fly indefinitely, why wouldn't those be a better alternative? The planes would be far easier to keep in position, and wouldn't have the 100 day life limitation.

LiftPort Group and +US are doing this tethered but at a lower altitude
LiftPort Group (LPG) along with the Communication Team (+US) have not only demonstrated their Tethered Tower concept but have also secured KickStarter funding to complete the first stage of their overall business plan, which is to produce a Lunar Space Elevator by 2020! Their successes allows them to offer localized (not Global) customized communication solutions on an as-needed basis, even in remote locations where infrastructure is not currently available.

Wow, talk about off the wall ideas. A 5 knot wind will move the balloon 120 miles in a day. If the ground coverage is actually only 25 miles in Diameter the coverage shadow would move out of range in 5 hours. The "ground control" would need to be a team of dedicated X box game enthusiasts trying to raise and lower the balloon up and down to catch unknown - probably non existent - alternate air currents. I can't wait for the follow up to the sheep farm video that tells us how this worked.
Just think, If the telcos had not shot down the Bill Gates satellite Internet in the Sky concept we would not be seeing giant Trojans floating above the sheep farms of southern NZ.

Nothing wrong with lighter than air vehicles for the job but they need to be powered vehicles and use a gas like methane or ammonia that is easier to contain.