Fon, in case you didn't know, is a WiFi community that allows registered users to use other users' WiFi services, provided they are within range of the users' access point.
The service also allows broadband users to generate income from their WiFi service by allowing non-Fon users to access their router on a pay-as-you-go basis, and the Fon user gets 50 per cent of the revenue stream.
The service works by securely locking off 512 Kbps of downstream broadband capacity to the Fon software and then routing the IP connection via Fon's servers.
Since, in theory at least, all Fon users are either registered for free service or have a payment card plus email address if they're a paying non-member, Fon can trace users if they do anything naughty.
That having been said, spamming is only possible via third-party POP3/IMAP servers and, since all Fon calls route via the FON servers, any dodgy downloads etc., can be locked down by Fon itself.
It seems like an excellent service, in fact, so the big question is why BT Broadband - an ISP that is not exactly reknowned for being innovative - is the first in the UK to actively promote Fon?
Of course, any wireless broadband punters can register for the free Fon service, provider they share their WiFi connection, but BT Broadband says it is actively promoting the service to its subscribers.
At the moment, Fon-using punters are a bit thin on the ground - here in Sheffield, for example, home of Chez Gold, there are only 12 Fon registered users, including yours truly.
Still, it's a start, and the service is free to register and use...