I used to do wireless security as a business, I gave up after i realized how stupid people were with this. You can inform them and they won't fix it, you can offer your services at a reasonable cost to fix it and they will do nothing. They may claim they will secure their own equipment, but until they get hacked or blamed for something a hacker did using their connection, they won't do anything. We have driven with my libretto and yagi from the shop to Metzgers house and hit over 200 WiFi access points one way, about 70% were not protected. At least half of the ones I see won't even make you research their system to find the IP ranges, they will happily DHCP you an address.
There is also talk that their will be open wireless available for public use in the entire downtown St Paul area legally. I don't see how they can do it being as it would effect the buisness of the local ISP's pretty significantly, but that is what I have heard. I know there are other cities doing the same. There are also a number of public wireless "hotspots" that are freely available to those within range around the cities. Most at resteraunts or coffee houses. The Keys Cafe on Lexington and Larpenteur for example. I can be anywhere within a few hundred yards of the building and get fast internet without using any specific antennas on the card, just the normal cisco.
BTW Enes, if you want to know the ip you show up from at any given location, you can hit
http://www.whatismyip.com and it will tell you. I have a script to hit it with lynx, makes it quick and easy.