WordPress MU

Is there some place I can put the JavaScript so that it will always execute, regardless of custom theme/templates?

We've got a 30+ user MU installation where people are free to customize & create their own themes. But I've got a piece of JavaScript (web stat tracking ping) that I'd like to ensure is *always* executed on every page render. I really don't want to have to run around asking people to put it into their custom themes.

Tnx- N

Maybe a plugin added to the mu-plugins subdirectory...