Hey, I didn't realise that Wordpress had a public Subversion repository; you can get the latest code here:
I just checked out a copy, and found to my great surprise that the plugin we've built actually works with the new code - excellent! Of course it looks terrible, as its style doesn't match the new Wordpress all that well, but at least it runs.
It's nice to see that the new Wordpress (v1.6?) has an action to allow adding namespaces to RSS feeds, and also to add items into the <channel> and <item> elements. (That will make our code look a little nicer when it comes out...). It seems that the posting logic from post.php has been moved into a library (admin-functions.php) as well.
edit_form_advanced hook might be handy for us, although we want to replace the description box as well, so it would be nice to have a filter or an action around there. Perhaps an action at the start of the edit form code, so we could call
ob_start() there and
edit_form_advanced, then modify stuff as required.
Is there a mailing list for this sort of thing?