I'm doing some work on the multi-db plugin to:
a) make it's error reporting friendlier
b) making it more failover ready for sites with multiple servers / replication
c) fixing some little bugs people have come across
I have a few different approaches I can take with the rewrites so I'm going to release a couple and hopefully get your opinion on whether certain versions speed up / slow down your site, cause additional errors / remove any errors you have.
The first beta test is attached to this post, it is only the db.php file - you will need to already have / or set up a db-config.php file to test this (it is primarily for those who already have a multi-db set up and working configuration).
Just replace the db.php file here with the existing one and things should carry on working as before.