Building communities through social networks ?

Everywhere you turn blog posts, tweets, diggs, The Wall Street Journal, USA Today, etcl are telling us we need to establish communities. I have @jeffpref on Twitter; this blog, a Facebook account; FAN Page, http://tinyurl.com/oa6tsf; and @BestHomeAgent on Twitter. I have a LinkedIn account and a Plaxo account. What I am now reading is that you need to link multiple social networks together, refer to others in whatever platform you are posting.
How do you build a following talking about Durham Homes, Raleigh Homes, Cary Homes, Chapel Hill Homes, real estate in general, affiliate programs, lead generation, training, etc., etc.?
Post insightful comments in communities that others have established. And do this while you are milking the cow, feeding the children, making the sales calls, watching 24 and Fringe, and taking-out the garbage. Who has time? Who can afford NOT to post on multiple sites? Email certainly does not work anymore, without double opt-in. Tell me your success stories and we will share ours with you. Follow us. We are pretty creative and some thing even brilliant. You decide.

Jeff Johnston,
CEO http://www.besthomepro.com
Twitter @JeffPref
http://www.jeffpref.com