CP+B have done similar things, and tried to explore how crowdsourcing can create buzz (e.g. with Brammo) .. I think at one stage they even decided to ebay the services of their designers to create a sense of the agency's openness to 'new'.
It does seem that aesthetics aren't the main driver behind branding decisions any more. It's impossible to stand out by having the nicest looking identity.
Taking an approach like this makes sense on lots of levels, especially when marketing budgets have been reduced; create a couple of reasonably strong memes, which last long enough to seep into the public consciousness before they die .. and gain phenomenal exposure without spending too much. Gap get to create the hallowed 'relationship' with the customer by involving them their own brand 'journey'.
I did make myself slightly sick after reading back over that last sentence, but to an extent I think it's true. We all build up relationships with brands over time, and the course these relationships take can be manipulated.
http://www.idsgn.org/posts/gap-turns-to-crowdsourcing/