Well I don't agree that you shouldn't put it online at all, instead you should be smart about who you add as friends.  I have only a few "friends" on those sites, and all of them are people I personally know and trust.

Those people who add everyone in the world need to get it under control and realize that they shouldn't add people they don't know just because they are funny or cute or have something in common.

As many of you have stated, I can see how employers would get a lot out of myspace/facebook if they are hiring for positions where they need someone they can really trust.  The funny thing is, I am 100% sure there is nothing on my sites that would incriminate me, but I still would rather they weren't looking which is why I stay private.  I've found some coworkers on Facebook but I haven't told them I'm there or added them, just to be safe!  What's innocent fun to one person may be considered bad to someone else.  Although I'd still think everything I do online is A-OK, but you never really know what people think is bad.  Maybe someone doesn't like my opinion on a certain topic, or maybe they think I shouldn't be friends with a certain person, that's why I stay private.