The majority (51 percent) of wireless access points in New York City are completely insecure, either using no security whatsoever or relying on WEP, which is all but useless. That number excludes publicly accessible hotspots you’d find at a café or park, meaning that a majority of those blue little routers sitting in the corner of every New York City apartment can be broken into with little to no effort. The above video shows how easily it is to crack WEP.
Note that WPA can also be cracked, but that requires a little more effort (though just barely—this stuff moves fast, as you can imagine.)
Those are some of the findings of the most recent Wireless Security Survey, which is conducted by RSA. Other tidbits of information—that London has the most wireless access points of any city on Earth (12,276 of them, which is some 3,000 more than New York has); Paris has seen 543 percent jump in the number of wireless access points—pepper the report but aren’t nearly as interesting.
Again, I feel like I say this every other day, but you really ought to secure your Wi-Fi router, especially if you live in a densely populated area, like, say, an apartment building. That means WPA or greater, because all it takes is one kid with a few minutes of free time and the will to do some damage to get you into hot water.