not assigned users in multisite can still login

[obvio]

I'm not sure if it's a bug or the required behavior but I've set up a multisite network with 3.0 and I have a few users which are assigned each to a site and then 1 user (role=subscriber) which is not associated with _any_ site (as seen on the table in .com/wp-admin/ms-users.php), this UNASSIGNED user can log in to all the sites in the network and the redirects to the main network dashboard.

I thought a unassigned user should be treated like "pending/awaiting moderation".

[nacin]

Users can't be associated with zero sites. They are assigned to the "dashboard site," which is set in ms-options.php, in the role specified in ms-options.php (default Subscriber). This defaults to the main site.