We recently completed the following report: "10 Ways Having A Customer Forum Is Different From Having A Facebook or Twitter Page". You can download the full report here. We are not suggesting that you don't have a Facebook or Twitter page, you should, but this report shows how important it is to create a central hub to pull together your external community ecosystem and take advantage of features and benefits that only a forum can provide.
In it we cover what kind of customer and member information you have access to through a forum that you don't get with Facebook or Twitter. We discuss the things you control and own with a forum vs a third-party site. For example, with your own forum you own the data, have complete control of the visual design, and can decide what, if any, advertising appears on the forum (e.g. calls to action for your products). We also discuss specialized customer experience and support features such as product Single-Sign-On and e-mail integration that you don't get with sites like Facebook, Twitter or LinkedIn. And we discuss both the SEO implications for public sites and the ability to manage different levels of access and member types for both public and private forums.
Enjoy the report!