Sounds straightforward to me -- Google is subsidizing the installation of faster, free wifi at all Starbucks. If you are asking what Google gets out of it, probably good PR, their name in the network SSID, and of course, the more people use the internet (on average) the more money google makes.
> the more people use the internet (on average) the more money google makes.
People tend to forget about these indirect effects - changes in habits, behaviours, economies. Anything leading to "more internet" or "more computer" in our lives will, almost certainly, lead to more revenues for Google.
Also, something I didn't think about, but if this push forces other companies to follow suit, and makes free wifi more standard, then this indirect effect could be pretty big.
