Social media in not a complete solution but a small piece of the marketing puzzle. If used in conjunction with traditional marketing, networking, etc. if can be effective. But not on it's own.
What it does enable me to do is stay connected with existing clients. Most of whom have a Facebook (etc) presence. I also use it offer small branding tips and to promote projects that I have worked on (a portfolio timeline if you will) which also helps promote my clients products.
And don't forget that the more you blog, Facebook, Twitter, etc. the greater web presence you have and the better you show up in search engines.
