If you have read Scott Ambler's recent interview on Agile which I think he did a great job of explaining in a high level view of what Agile documentation is all about, then you may have more questions about how people are really documenting "stories."  My company has been practicing Agile for 2 years now and we have evolved from the many retrospectives to try and get the "right" level of documentation at the "right" time.  We follow the User Stories Applied by Mike Cohn methodology for User Stories but are constantly searching the web and seeking out others that are Agile to see what their artifacts are.  We have recently decided to start with models (following Agile Modeling,  by Scott Ambler) to capture understanding of the requirements and then put that understanding on a user story level which we are constantly adding information to the closer we get to development time.  What I think that we are missing from the discussion is exactly what people are doing and I would like see what other people's processes are when it comes to using user stories and documenting requirements for the developers and the stakeholders. 

Here is another reference on this topic, a short article "YAGNI Your Requirements Documentation" related to this topic of agile documentation. i hope you find it useful.

~ ellen

Ellen Gottesdiener

EBG Consulting

www.ebgconsulting.com

Alistair Cockburn writes an article on why use cases shoulod sgtill be used for agile projects.  Acces via a link on this blog post