On the one hand, it is a wonderful medium in conveying ideas, building lasting relationships, sharing information, periodically keeping in touch with acquaintances, and so on.
On the other hand, from my perspective anyway, one must always be cautious of cyber predators, friendships that may go sour, cyber bullies, employers accessing information about you, and so on.
I guess it's just the world we live in, with "pros" there are always "cons". Not to sound as though I'm paranoid or overly cautious, but with so many reports of shady Internet practices, I think I've developed a healthy guarded approach towards new technologies in general.
To help those like me [guarded], as you might imagine, there are numerous resources available to protect one's privacy, and address other concerns one may have. Below are just a few useful links I came across:
Social Networking Sites: A Parent’s Guide
http://www.ftc.gov/bcp/edu/pubs/consumer/tech/tec13.shtm
Social Networking Sites: Safety Tips for Tweens and Teens
http://www.ftc.gov/bcp/edu/pubs/consumer/tech/tec14.shtm
Prevent Cyber Bullying
http://www.cyberbully411.org/who-is-targeted-by-cyberbullies.php
Social Networking in Plain English
http://www.youtube.com/watch?v=6a_KF7TYKVc
I've sort of developed my own quasi "set of guidelines" to follow:
1.] Keep personal information to a minimum
2.] Know your audience/"friends"
3.] Avoid religious and political topics
4.] Any memberships or affiliations listed should be professional in nature
Wait a minute, looking back on my quasi "set of guidelines", maybe I am just a little paranoid! As I begin to become more comfortable with "Social Networking", I'm certain my paranoia will cease.

rs. As a blogger, there is the ability to tailor your message(s) in order to promote productive ongoing dialogues to a desired audience.