Mobile blogging is an interesting, and potentially very powerful, development. The idea is simple: snap a picture with your camera phone, e-mail the picture with a bit of text to a particular e-mail address, and bingo, it appears on your blog.
Now multiply by the number of camera phones out there.
In fact, there are only two things missing to make this scheme a publicly driven surveillance system: a search engine capable of indexing and retrieving the images, and some way to link images to geography. Want a photo of the traffic accident at 5th Ave and 59th street on June 12th? Run a quick search and see if someone snapped one. Want to know where your girlfriend, boyfriend, or spouse was Friday night? Plug in an image and you may find out. (Or they might find out where you were...)
Social effects? I'm not sure. Especially once you throw the occasional Photoshop job into the mix. It's worth thinking about, though, since early image-based search engines already exist, and modern phones already know their locations for 911 service.