I recently did some experimenting to see what the wireless situation was in Toronto. Since I was going shopping downtown and had to take my laptop with, I figured that I would not power it down and left it running in my bag with the NetStumbler program activated. There was no external antenna used and the bag probably detracted even more from range / SNR.

After taking the King streetcar to get downtown, I did a lot of walking through the busiest sections of Front Street and Yonge Street and even an office tower and the Eaton Centre.

Here are the results of my experiment:
Time Active: ~ 4.5 hours (recharged laptop's battery over lunch)
WiFi Networks found: 92
Networks without WEP: 51 (55% of total)
Networks with WEP: 41 (45% of total)
Best SNRs from no-WEP networks: 46,35,31
Least secure AP: Linksys - 17 instances (33% of unprotected)
"Bad" SSIDs: 20 (39% of unprotected)

Some notes:
The Eaton Centre seems to have a large number of WiFi networks and at least 10 are not using WEP.
Linksys seems to be the most "unsecure" brand of AP (perhaps due to their default "linksys" SSID and no WEP enabled by default).
Many networks use easy to guess SSIDs such as "default", "linksys" or even their company name (at least a few did the latter).

Overall, most people just don't seem to care about securing their networks even with decidedly flimsy WEP encryption. However, my estimated rate (55%) is a little better than the 60%-70% rate of no-WEP networks others have reported from their tests.