shared login url for intire network


We have a rather large wpmu setup and most of the users asks about the login url to their blogs. Is it possible to have a shared login url so the login would allways be domain.tld/login and after login then redirect to the users administration panel ?

If one logins now, though that url there is a notice that you can manage your site, and when you click the administration panel link you need to login again to get access.