[Albright]

You should be very leery about connecting to wireless networks you haven't set up yourself, either with a Kindle or with any other device. You don't know the intentions of the person who set it up. It would be pretty easy for a ne'er-do-well to set up a wireless network without encryption which logs data sent to and from banking or shopping sites, then wait for some sucker to come along, connect to their network, and then visit one of those sites. Even in places where you're invited to connect to the network, like hotels and coffee shops, it's probably a good idea to avoid any network transaction which involves sensitive or personal information - perhaps the network you're connecting to was actually set up by another customer with ill intentions, or perhaps one of the employees has come up with a way to make a little money on the side. These sorts of hijinks are referred to as "man in the middle attacks" - though "attack" is sort of the wrong word because it's more like passive data collecting.

The internet's a dangerous place. Good luck out there.