When developing a strategy for social media, consider what the participants will gain from participating within the community. How will your community help them, and their existing networks? If I already develop content for a community or my own blog, there's a big disincentive to start developing content for a new community. You have to provide some powerful incentives to encourage participation within the new busy networked world of social media.
One idea that I think makes sense for web 2.0 websites where the community is the focus is to allow people to contribute content through trackbacks from their own blogs. There are forum systems available that allow trackbacks, consider this for all of your web 2.0 community sites.