Just read this thread in its entirety over the last half hour. Now I'll try to address the more recent points...
I've agreed with both sides of the argument of using social networking sites to fire/hire/not hire/whatever an employee. However, to me there are certain flaws in the arguments presented.
Yes, posting pictures, videos, your hobbies, whatever on your publically visible Facebook is your fault, but is also under your control. I agree with the view that if you put it up for those to see it, then anyone who sees it can judge you based on that. Take this (somewhat specific example):
You happen to like drinking at a bar every other night with your buddies and you happen to get quite rambunctious most nights if not every night. The next day you go to work and you're very professional. The twist, however, is that the bartender who always serves you your favorite drink also knows your boss. Your boss happens to find out about your drinking (problematic or not) hobby and fires you based on that decision.
Now how is this different/same as posting pictures of yourself drinking online? Difference, you're voluntarily posting pictures of yourself on a public profile viewable to your employer should they choose to make a search for you (motives aside) rather than your employer finding out you drink by chance. Similarity, the end result is the same.
You may think this is a poor example, hell it might be. But I think this illustrates the discrepancies in the semantics of your arguments. Your views on the internet and how social networks and their "rules" of communication are the foundation of your arguments. I believe Jovian equates the social norms of "real-life" communication are applied to the internet. Te objects to judging someone on their extra-curricular activities, no matter the environment. I also find that bgc and Zircon view a slight difference to Jovian in that since the things you put on the internet (without a private setting/password) IS public AND (typically) readily accessible, you should be more responsible of how you display yourself.
Bottom line, face reality, protect yourself. I'm not saying you're not entitled to your opinions, Jovian specifically, but there's not much you can do about it. I do agree that it's kind of low for employers to do a search for you, but it's something that you have to protect yourself from, not get them to stop.