The arrival of every new social media tool, be it Facebook, Twitter, FriendFeed or whatever, is inevitably followed by conversations about the best way to use it for marketing purposes. Ideas are floated, advice is offered and someone creates a best practice guide.
And there's nothing wrong with that. Except that it's putting the cart before the horse. It's fine, indeed imperative, to know what the new tools do. But before you use any of them, you have to be certain of the context in which you're marketing and the goals which you're seeking to achieve.
Only then should you look at the tools available so as to decide which of them, if any, are best suited to meeting those goals. Tactics follow strategy - not the other way round.