This question builds on a comment of Shane's in a previous meta post on what can be achieved using a theory Q&A site.
I've spent a good deal of time on Jeff Erickson's lovely problem about unshuffling a string, and during the proposal phase, on his question about the complexity of minimum sequences in generalized Rubik's cube. However, I haven't posted any responses to those questions because I didn't end up with an answer.
Most of what I've done is discover dead ends and approaches that don't work. These might be useful for someone to know so that they don't spend time on the same issue or if they'd like to pick up where I left off. Unfortunately, the Q&A format doesn't seem naturally suited to this style of inquiry. A wrong answer isn't an "answer" per se, and a detailed discussion won't fit in a non-nested comment thread.
The question: how can the CSTheory Q&A format better be used to support these kinds of parallel group investigations into problems?
One idea is to adopt the convention that "answers" to open questions are to be regarded as a discussion of possible approaches, rather than literal answers or partial answers to the question, then to encourage development of these approaches in the comments. The downside is that these comments are not nested.
Another possibility is to fork new questions concerning particular avenues of inquiry with links back to the parent question, perhaps with a dedicated "subproblem" tag; this might lead to a messy proliferation of subquestions.
Has any better format been discovered for collaborative investigation of open problems on other StackExchange sites, in particular, MO? Are there other features in StackExchange we can activate to support this process? Or is it better to instead restrict these kinds of investigations to blogs and wikis, as was done in Polymath?