Hi there,
There's a new plugin, free, Apache2, available on Marketplace starting this morning. Short URL: http://goo.gl/5ZjyJ.
Source code: https://github.com/rdumitriu/jira-qanda
Wiki: https://github.com/rdumitriu/jira-qanda/wiki
Get it touch with us here: http://goo.gl/J29jC
I hope you will find it useful.
Edit: Nic requested a brief description. Here it is:
Once installed, it gives you an extra panel on your issues: the questions panel. People can use that panel to add questions related to the issue and receive answers. Once one or more answers are approved, questions can be added to the description of the issue by a simple click.
To keep track of the unresolved questions, a gadget is provided. It looks for issues in the specified time interval - check the configuration - and shows you unresolved questions. Having it near your activity stream will point out very quickly what piece of info is missing to the developer.
Please read the wiki for a detailed description.
Edit: Thanks to all for offering this plugin a warm welcome!