>Certainly this does concern ISPs. Running an open wireless network will often violate your terms of service. But despite the occasional cease-and-desist letter [...]

Can someone explain this to me? How does your ISP know that you're running an open wifi network? I doubt they drive around to every customers checking for them.

That said, I've been thinking about running an open hotspot. If it's on a different vlan, with only port 22/53/80/443 open and speed/number of connections throttled it shouldn't cause any problems for anyone, and it's just a nice thing to do.