Is Big Brother Watching...or Are We Inviting Him to Dinner?

I posed a single question to my facebook wall yesterday which has created a lot of discussion so I will pose the same question here to get your take on the latest situation with Edward Snowden, the 29 year-old former IT contractor who disclosed our government's classified "PRISM" datamining program which looks at patterns in calls, emails, etc. (but does not read content without a warrant):

Question: can we honestly have a "reasonable expectation of privacy" if we're all constantly "tweeting" every aspect of our day, publishing our respective status updates and "checking in" to every single unimportant place that we visit?