Guessing no, because of the Node.js plugin architecture ("need to call into C or C++?", "full access to the filesystem"). Really only the UI seems to be done in WebKit.
From a quick glance it looks like its architected the same as Light Table (Local node server that accesses the file system and a decoupled UI that connects over http and uses WebKit).
If it works like that it could run in the browser. Not so easily from anywhere though