Anyone using Javascript on server side?

I see plenty of frameworks try to promote Javascript to be used on server-side:

http://en.wikipedia.org/wiki/Server-side_JavaScript http://www.joyeur.com/2009/01/14/joyent-acquires-reasonably-smart

I seriously doubt exiting server-side developers would use Javascript for server-side programming.

It doesn't make much sense to me as there are plenty of mature languages for server-side.

so is it just for front-end developers to apply their Javascript magic on server-side?