Introducing Acre. I’m losing track of all the server-side JavaScript hosted web application platforms now. Here’s the Freebase contribution to the genre, complete with IDE, templating language and strong integration with Freebase itself.
Sign in with 
OpenID
I must be missing something, but I really don't understand - what's the attraction of server-side Javascript? When would I want to use it?
When JavaScript is your favourite programming language, I guess. It's also quite neat to be able to write code which can run client-side or server-side - validation logic for example.