Hello Alex,
we have been thinking about providing some hooks in TestRail to better integrate it with other tools, including auth/directory services. We plan to eventually allow admins to change the authentication method by writing a custom PHP file. And since PHP supports LDAP natively, implementing single-signon (also with MS Active Directory, if desired) would be quite easy (we also plan to ship an example for this).
I cannot say when this will be available, but we definitely want to make TestRail more flexible in 2010 and this would be a very good fit.
Regards,
Dennis
Dennis Gurock,
Director & Co-Founder
Gurock Software