Once a person edits a page, can he/she automatically send out an email to all Wiki members to view that page?

Kathleen,

Those who have email notifications enabled will generally be notified of the change, though if we've sent them an email recently our system may hold off to avoid sending too much email. We're working on a design for the notification code which handles that whole process better, since it's not really what most users seem to expect when they use a wiki.

In the mean time, that's a good idea as a distinct new feature -- sort of a "this is important, you should come read it" button. We've thought of some other things in the same vein but will be taking this on seriously in the near future.