WordPress MU

Ok, this is a big one I'm afraid.

My understanding of the current security mechanisms is that a user can register themselves for a new blog (sub1.mydomain.com) which will mean their security settings are relevant for that subdomain/blog only (i.e. sub1.mydomain.com and they will not be recognized in sub2.mydomain.com).

What I am after is everyone on my wpmu installation to be registered and have privileges across all blogs. Is this possible? Has anyone done this?

From a first glance it seems as though you have to change the domain to which cookies are written (write them all to .mydomain.com with the 'wp_setcookie' pluggable function).

I'm sure it can't be that easy...

Anyone?

Only current method I know of is to add them in to the Site Admin list. On my old setup, I added my 'drmike' name to the "users allowed to log in as Site Admin" list (I think it was Dashboard -> Site Admin -> Options) and it allowed me to log into all the blogs.

That's probably overkill though.