Today, John Slater and I posted some messaging documents to Spreadfirefox.
One of the documents helps to explain Mozilla: who we are, what we do, why we're here, etc. The other document evangelizes the benefits of using Firefox. Our hope is that people will use the docs and then share feedback about what resonated, what didn't and how we can tweak them for future use.
These are not final documents. They are meant to be a living, breathing reflection of our community. We plan to release subsequent revisions based on community feedback. If you use them, we'd love to hear from you about your experience.