I read an interesting guest blog post today from Gary Arndt of Everything-Everywhere.com. Gary was a guest blogger on Problogger.com and you can read his post here http://www.problogger.net/archives/2010/11/08/why-social-media-is-a-better-investment-than-seo/
Gary thinks focusing your efforts on social media instead of SEO provides you a better ROI. Gary's debate centers around Brand vs. Individual Authority. Since Google loves big brands and seems to favor them in the search rankings, small businesses and consultants have a hard time ranking highly. By building your individual authority using social media, you can build a large following. The individual authority won't necessarily give you high search rankings for particular keywords, but it will generate a lot of web traffic and probably lots of business for the little guy.
We all know SEO is a lot of work and your rankings can change overnight when Google implements one of it's infamous updates. If you aren't trying to game Google by using Black Hat techniques, you actually benefit from the Google updates because they knock the gamers down in the search rankings.
Social Media is no picnic either. To become an individual authority, you have to spend many hours every week Tweeting, updating Facebook and connecting on LinkedIn. Like SEO, social media is not a one-time event or an occasional event. Success in SEO and social media takes a focused, consistent effort.
I agree with a lot of what Gary says in his blog post but I also think you need to focus on both SEO and social media to be successful online. SEO provides you long-term search listings while social media ranking has become a real-time event. Your Tweets, Facebook updates and blog posts come and go quickly in the left column of the Google Search Results page. If you spend a little time adding some SEO to your blog posts, you can rank for years in the natural search rankings (the middle column of Google).