Edit: I should have given a little more value on the post. I left node for Scala because the advertised code sharing wasn't worth having to work around an event architecture that I found hard to debug (as I've mentioned elsewhere) and I too considered Erlang before settling on Scala due to our previous java experience and my co-founder's knowledge of people in the Scala community.
But fundamentally, node.js isn't interesting if it's not in Javascript. Actors seem like a better model than futures tacked on to callbacks, and frankly javascript's quirks (like having to use require.js for modularization rather than a feature built into the language!) IMHO don't make for a compelling case.
I'd use node.js on someone else's project, but I don't know if I'd pick it for my own.
Even more than that, I think that the entire notion of what a server is for is changing rapidly away from "server-side MVC" to a far more rational (not to mention more efficient) dual role of "initially serve a client" and then "handle messages from the client". Server-side manipulation of client state is a horrible, terrible idea in any language, and right now node is suffering from cultural/technical momentum of wanting to do things that way. Once that impulse goes away and alternatives become more popular and well-understood, I think node will get even more popular.
Oh wait, JS compile to Erlang? Wouldn't it make sense to do it the other way around?