Jeff,
thank you very much for starting with concrete details. Although I don't know yet how this discussion may be done best, I don't want to waste time and tell you want I think important about #3 and #10 (not speaking for the UAB here).
For #3, I would be happy to have SOME way to expand and collapse individual postings and subtrees, perhaps with a "+" and "-" toggle similar to windows explorer (sorry, or in Mozilla preferences menu). The most important reason is that, for instance, within the use case of humanities discussions, threads simply become too long to keep orientation within the thread.
For #10, the idea is to allow users to read much text in a narrow pane without being forced to adjust the window width each time they leave a page with wider content (e. g. navigation) and enter a text intensive page. (Narrow reading panes might irritate programmers but are important for text-intensive work, and newspaper columns are therefore narrow since many decades). At the same time, the saved space could be used for breadcrumb navigation in a left-hand side pane instad of wasting space in the top for the breadcrumbs.
Regarding #2, #6, #7, I do think they touch your communities of practice work and I would like to learn more about it.
