Sonny Cloward of
CERF has a nice blog post on how he's using del.icio.us in his organization:
Bootstrap-a-licio.us.
So, I gotta say: I'm not sure of the value of an organization having a tag.
If you want to control what goes onto your web page (like Sonny's example) it's easy enough to make the relevant del.icio.us links be attached to a user or a combination of users (you can even add tags in there so it's only a certain tag from a certain user). That helps you to get over the issue of editorial control.
But part of the point of del.icio.us, for my money, is the social aspect. The findability and serendipity attached to tagging. That is benefitted by applying a tag that speaks to an issue rather than an organization.
-webb