It's beginning to feel like we're unable to go even a single week without learning of a public official caught in an affair, but last week's discovery of the affair of CIA Director David Petraeus came as a shock for a couple of reasons. David wasn't some mere politician, but a decorated war hero who most recently sat at the helm of one of the United States' most important agencies. His decisions made things happen, and with that sort of power comes a lot of risk.
It's since been discovered that it was Gmail that managed to expose the affair, proving that when you're an important asset to the government, the term "personal" gets heavily skewed. While you and I might be able to remain confident in our Gmail accounts being locked-down and out of prying eyes, the FBI seemingly has every right to peruse your personal e-mail accounts if a possible risk exists.
In this particular case, the FBI was beginning to believe that David's Gmail was being targeted by hackers, or was already compromised. It's not difficult to see where things went from here. As the account was perused, the affair was discovered and consequently handled. It's not mentioned if the FBI gained access to David's account by way of pressure to Google, or if it simply had David's password. On a similar note, it might be easy to assume that David didn't properly cover his tracks, but it could be that given his position, there are strict rules about purging e-mails. That in itself may lead to suspicion from the FBI.
According to the Wall Street Journal, the reason the FBI keeps on top of this monitoring is that there have been multiple instances of not only official e-mail accounts being targeted, but personal accounts as well. And ultimately, the reason David was forced to resign over something that doesn't seem to have much to do with national security is that it opens up the doors for possible blackmail. Given that, it seems we should be thankful this came to light.