Share Taxonomy between groups?

I was wondering how gdo is setup and if it's technically feasible to share taxonomy between "some" groups? I think geographic groups in particular would benefit from this.

I just reorganized the Southern California group - which is essentially equivalent to a "BosWash" group (if there was one). With Southern-California being the second largest urbanized region in the U.S. yet it's similarly dispersed, my goal is to help users in regions that don't yet have a formal group to connect. As I see it the best way to do this is to have a taxonomy similar to how Craigslist defines regions. I went with a combination of wikipedia "locale" definitions - plus area codes.

The Current Problem

If content is posted in another group (e.g., the LA group, or High Desert, etc.) and "cross posted" to the Southern California group, then taxonomy in SoCal can't be used or added later. Therefore, I'm curious if it'd be possible to share my "Area categories" with other geographical groups in SoCal. Obviously, group managers would need to agree to this, but I thought I'd start with the technical possibility.