Telstra through BigPond has become the latest ISP to try to monetise customers mistyping of URLs (or following broken links).
The idea is simple, your ISP runs a DNS server that your browser goes and queries when it is trying to find a web page (the DNS relates domain names as they appear in URLs to the IP addresses that routers atually use to make connections). When the server identifies that there is no match for the domain name then normally an error is returned to you - and what happens depends on your own browser settings.
The monetisation comes by sending mistyped requests off to search and producing a search page with typical sponsored links. There is a more advanced version of cyber-squatters who actually register the domain names of frequently mistyped domains (a good example is aple.com).
ISPs, of course, justify it as being a "service" to users. I guess personally I don't really mind because I will ignore the returned page anyway. But is it really just indicative of the whole damned relationship between telcos and customers? Isn't it really just abuse of the position of a service provider to attempt to profit from a customer's misfortune?