Oh, no, it's not.
Email never dies. Your potential employer can and will find your beer bong photos on Facebook or Myspace.
And real people have feelings.
One of the benefits/downsides (depending on your perspective) of Facebook is that every genius on it can share every single thought he/she has -- everything from "I'm hungry" to "Wondering why my neighbor feels it's okay to clomp around in high heels at 1 a.m. and wake me up????" *
Private thoughts are okay. In fact, they're good. Most of your FB friends do not care that you regret that cheeseburger with fudge that you ate last night. Also, your FB friends don't want to hear about your colonoscopy. And while they might not care about your dietary habits, they do have feelings.
So think twice before you post. If you're hosting a wedding (or some other massive social event) to which not everyone is invited, you might not want to post every detail every ten minutes.
And if you're about to bad-mouth someone? Skip it. Chances are one of their friends will see it. Even if you post on someone's wall (vs. posting a public comment), all of their friends can see the wall post.
Nothing on the internet is private. And there are people out there in the real world -- people with feelings -- reading this crap.
* Tip from Wired Magazine: Hunger and fatigue are never good facebook posts.