MY COMMENTARY:
When Starbucks first launched My Starbucks, I visited and was impressed by the organization and authenticity of the forum (letting the good, bad and ugly voices in), not to mention the amount of feedback they were getting.
I think My Starbucks is a big part of the turn around but not necessarily because Starbucks heeded useful feedback (one of the more vehement threads on My Starbucks has been about Starbucks recycling cups in every store. Still not happening). Simply engaging customers rather than keeping the old "We know what you like" vibe going was a big, positive goodwill step.
Contrast that with Best Buy's Idea Exchange (IdeaX) which has a much more lively "We're listening and acting" tone to it. The complex and innovation-driven nature of Best Buy's business makes IdeaX inherently more relevant (getting all of that customer feedback right when they're exploding their private label tech offerings? Sweet!); so much so that more than one of my CE colleagues has told me that they go to IdeaX to get ideas for their own products!
Every retailer and brand should have some version of an idea and feedback forum.