I'm looking for a way to share the user database across several subsites, each installed with WPMU. We have regionally (geographically) - based directories. Members, who are paid subscribers/pay-to-blog, should be able to access groups on more than one regional directory without having to pay again, or create two separate blogs.
example:
Someone looking for information on boston.ourdomain.com may also need to get to information on newyork.ourdomain.com. They should be able to access that information and add groups to their page.
Make sense?