Apart from the huge PR value (Dell, salesforce.com, Starbucks & whitehouse.gov all got a LOT of press from these) that communities like these bring the company, they are very good at some things that traditional roadmap planning processes suck at: 1. De-duplication: When communities coalesce around similar popular ideas, it's easy to understand patterns of requirements. Traditional request processes are black holes for this reason. 2. More Democratic Prioritization: Since there isn't a good way for smaller customers to coalesce, PMs are often stuck implementing requests from their largest customers. This solves that problem. 3. Partner promotion: As a platform provider, you want to be able to support complementary partners. Unfortunately, partners often don't know what to build, or have poorly targeted products. If you were building in the force.com ecosystem, you could start your customer development right in the salesforce.com community. This was important to me because I had a lot of friends in the partner/developer community and wanted them to succeed.