I am remiss in posting a link to Google's peek under the kimono for usage of its free Mountain View network: The network that Google was able to build, a little late, but generally to good reviews, sees a lot of usage, the company's "alternative access" team posted to the Google blog last week. (Yes, I'm late to the game on this one.)
They have over 400 routers covering 12 square miles, which conforms to the general expectation these days of needing about 35 to 40 routers per square mile. They see 15,000 unique users each month, although we don't know with their methodology whether that's uniquely created accounts, since you can create disposable accounts on their system. They transfer 300 GB of data each day to 100 different Wi-Fi devices. Given the different number of adapters, that's the iPhone, 95 laptop cards, and four other devices (I'm joking).
Also interesting is that 95 percent of their mesh nodes see some use each day, showing that it's not just concentrated usage. I'd love to see a histogram of usage, showing the amount of usage against the percentage of routers.
Will Google build more Wi-Fi networks? No. But I can see them putting money in different forms into new models of city-wide Wi-Fi that are already underway.