I like how it abstracts a server down to just a chain of modules that can be either a response provider or filter. This reminds me of the architecture of Nginx.

If someone could create a FastCGI implementation as a provider, this would be awesome. Then certain routes could be passed off to Ruby, PHP, Mono, (whatever) and simple things like static files, pub-sub, cache, etc can be handled by node.

I definitely like where they're going with the project and with the ExtJS team behind it, it should be a success.