Blogs can be a great way of communicating with your fan base, and letting them know what's going on with your products and future releases. The related comments let your customers communicate back, but they tend to be a short form, less engaging way to interact. They're great for customers who just want a quick way to show their enthusiasm or ire, but they tend to be less effective at omni-directional communication, and don't build the kind of strong social bonds as forum communities. Some communities (Penny Arcade, for example) use a hybrid approach, offering inline comments that are also posted into the forum community.