Rails - Mar 2006 - Can different models use different databases?

If you define the establish_connection method in a model to use a  
different database than the one defined in config/database.yml, will  
Rails run queries across both databases and do cross-database joins  
when necessary?  I''m using MySQL, and I know that MySQL supports  
cross-database queries, but I''m not sure if Rails supports them.

Thanks,
Christian