I hate to say it, but I am skeptical of Facebook as a marketing tool for small businesses or entrepreneurs. I have read the articles proclaiming how this business is doing great because of it's Facebook page and web 2.0 social media marketing. I have seen and tasted the Kool-aid. But I am not sure - too push the analogy a bit too hard - of the nutrition of the drink.
Blogs - yes, especially if you have readers. :)
LinkedIn - yes, especially if you have a good network of people, and don't succumb to allowing Larry the annoying guy from marketing into your network so he can spam your friends.
I can even see how a tool like Twitter can keep people in communication with one another during the work day. I especially can understand its usefulness for people like developers of software to help find solutions to problems "Hey I need a foo to do bar - can anyone help?"
But pure social media sites should be left to your family, church members and the softball team. It is useful, but not for business. You would not want your boss to be a 'friend' on your Facebook page.
I suppose if I put on my Seth Godin hat (would that be a purple hat?) - I might argue against myself and say "Brad, you are building up your brand - who and what you stand for - and that brand is what will be valuable as you sell or run your business." If I am authentic, then that is what generates a group around me and the value of that group.
Here is the rub: authenticity has consequences both good and bad. If my authentic self is completely into tatoos, and my body is adorned with them, then that might keep me from a job. The world does not necessarily value authenticity. Are you sure you want to blur the public and private?
When I lived in Japan, I was often struck by the difference between my Japanese aquaitence's inner and outer personas. Outside, they were salary men, bland, faceless, group members. Inside, they each had great passions for a variety of interests. They found it strange that Americans often wear our inner passions outside (we strive to look different) yet internally, we are all the same.
My argument against social media is much the same: are we ready to put our inner selfs on display, and accept the consequences thereof? Blogs, LinkedIn and Twitter all allow us to use our outer personas in public, but leave our inner selves hidden. Social media is predicated on the opposite.