Implementing an online community can definitely have a positive impact on a company's search engine optimization (SEO) strategy... if done properly. I'd love to hear how companies are integrating user-generated in this regards. Here's where I see the biggest value for search engine initiatives: while search traffic varies widely from site to site, you can generally say that there is an 80/20 rule. 80% of traffic comes from 20% of your core keywords -- the long tail being the other 80% of the keywords that drive traffic to your site. Using an online community, you can to some degree "outsource" long tail or niche content building to your customers. This video helps illustrate my point:

(link to video on Vimeo here)

SEO - Where Online Communities Fit In from Paul Biggs on Vimeo. 

Including the concept above, I see 3 areas where communities can impact SEO:

1. Capture the "long tail" of search by outsourcing nice SEO content to users, that the main site (run by Marketing) doesn't have the resources to cover
2. Provide additional keyword research by providing insights into what terms prospects and customers are using to describe your products/services
3. Improve overall search rankings by naturally creating a network of links in the community and to the main site that boost SEO factors

Does anyone have examples of this? Other areas of impact? If you want to learn more, you can see a recorded webcast here: The specified document was not found.http://www.jivesoftware.com/news/webcasts/register_seo?utm_campaign=Webcast-SEO&utm_content=clearstep&source=Webcast&cid=701500000009cpA&ccn=080909-Webcast-SEO_Clearstep&referral=clearstep