The AOL situation wasn't really due to a leak. AOL choice to release that information, they even had discussion forums set up but it simply a poor choice.

Lawrence Lessig hits on a hugely interesting topic though. Hugely. Whenever we get on to this topic at work the camera phone and YouTube debate comes up. If I wanted to film you and run the film on an obscure cable channel I'd need to have you sign a release form. If I vidPhone you and release it on YouTube then you'll probably be seen by more people (viral success allowing) and there's no strong remit for a release form.

You're right, I used "leak" very literally – a flaw in the system that makes something escape... in this case, I think the flaw was how AOL set up its research team, and the way AOL enforced their privacy terms.