So, for example the lua instruction file.open("sfs://192.168.1.1:2323/filename") will build a connection to the host and then you can read, seek, etc, on the file on a remote server (in this case the server described by ip=192.168.1.1 and port 2323) as if it is a local file.
There are two protocols, sfs (as above) and pfs. The sfs protocol shares the name space and file contents to every esp lua node, while the pfs is a private (yet still remote) file system for just this node.
I didn't get any feedback so it doesn't appear to be of much general interest, but I'd cleanup the code and push it to github if people are interested. You would also need to have a server to handle the rpcs (I've written a simple one in ruby) .