Is it still having some growth? If your asking yourself this and not using these areas to promote your business by then you may be out in left field. Social networking is truley growing by leaps and bounds. Take a look at Twitter, 150% growth in the last year or so and Facebook! ranked out of site by Google. For my buck, these two networks are worth belonging to and using to the fullest to interact with others. Therer is no better way to get the word out about your Blog/s or a business that you are trying to develop and get off the ground.
Posting a few words of wisdom, a short blurb about what you are doing will bring traffic to your website. You may not take notice of this traffic right away, give it a little time and you will see were the traffic is coming from. Search Engines and keywords are there and the major engines use keywords quite heavely but using Social Networks is a big plus.

