I'm sure it's simple but I'm knocking myself out trying to figure this out.

If a post goes from draft/private/protected to published how can I tell that in a plugin? Or heck even the other way around will be nice to know.

Actually come to think of it I guess I should also know if it was published then went to draft then got published again. I can maybe figure out this one by looking at ping status in AfterItemUpdate ? I'll try that, but it still won't tell me if a published post got edited for content, or from draft to published.

What I'm looking to do is find the first and only moment when a post goes to a published status. That way I can finish this little "blogging makes a phpbb2.* forum entry" plugin.