The default setting on most ip cameras is "public". I can't remember it atm, but there's another search you can do that exposes a ton of cameras of the form

<uniqueID>.something.com where something is setup by the camera makers to provide an easy way to share your cam. (This isn't anything new, I was thinking of doing some analysis on all the public IP cams you can find on google a few years ago).

Here's another one http://www.google.co.uk/search?hl=en&q=inurl%3A%22snapsh...

After the 1st page or so, the rest are all Panasonic IP cams.

I think the answer is to have IP cam makers default to private - just like routers/hubs/etc