authenticating through multiple database

hi, I am new to Ruby on rails and in need of some urgent help. I need to create authentication module for one my projects where I have multiple databases. One database is connected through LDAP and the other one is just an internal database which can be accessed directly through active record. Now, my question is, is there a way to authenticate against both the databases when some one tries to login? Does rails provide any such support for this?I have looked at couple of authentication gems(e.g : Authlogic, Ruby-Cas, RestfulAuthentication), but all of them seem to provide support for authentication against a single database.

Any suggestions will be appreciated.

Thanks, Muntasir