I guess I don't so much disagree with the idea of being careful on an unsecure public wifi, as I am concerned that so many people seem to think they only have to concerned about the unsecured wifi, not all the other hops on their connection. You know what I mean?
Oh absolutely. And heres why: http://www.wired.com/threatlevel/2008/08/revealed-the-in/ . In short, the researchers demonstrated that they could poison the upstream provider for Defcon's internet, such that all Defcon traffic went first through their server, before reaching the internet at large.
I don't think people here are suggesting that this is the only vector of attack against your system, rather that given the proliferation of unsecured WiFi networks it's just one of the more common.
When someone brings out the "ARP poisoning" add-on for Firefox maybe it will fuel debate on other types of attack :)
