Multi-DB: What's the plugin for?

I've got multi-db running and stable with 256 databases. I noticed that multi-db is listed as a plugin. It's not activated. The description mentions set up and monitoring the multi-db installation. I can't find any mention of this in the documentation.

Am I correct in that the plugin doesn't need to be activated? What does it do?

I get real nervous when it comes to doing anything with an operating multi-db install.