Yes, e-mail and instant messages probably should have better legal protection
Should personal information that people store online, like e-mail messages, photos and location updates, be treated the same as telephone calls or paper documents stored in a person’s home?
Right now, they often aren’t, in part because the Electronic Communications Privacy Act, which governs surveillance of what people do online, was written in 1986 — well before Twitter direct messages, Facebook status updates or Foursquare check-ins.
And Web users generally do not understand when and how law enforcement can get access to their information
I think this should depend on the 'public' nature of the information. For example, a private e-mail between two people should be treated more like snail mail. But a publicly-available photo on Flickr is exactly that: public. And a location update on Foursquare may fall in between, depending on with whom it was shared (i.e., individual, small group, or the world at large).
