Fon has been around a little while now, starting in Spain where the network is pretty good, even with hubs in Corralejo, Fuerteventura.
You buy a small Fon router, plug it into your existing router, and hey presto, you get your own secure Fon network PLUS an unsecured network which anyone in the neighbourhood can use, as well as your existing network.
If you've registered with Fon and operate your own Fon router, you can access anybody else's unsecured Fon network for free. If you haven't signed up, you can still pay for Fon network access, at a cost rather lower than that of The Cloud.
BT have combined with Fon to extend the range of wi-fi hotspots in UK. It's got to be a great idea, at least until Wimax gets here.
I'm not sure if Wimax has met technical problems or if there is a major hitch with the economic model. Keep hoping it will work. VoIP could knock the socks off mobile networks.