I think somebody was working on one in lua, but I don't know if they finished it.
If you write a Lua implementation or a lua wrapper for an existing C implementation let me know.
The walk function (which returns an iterator, successively returning tables with each file's stats in a directory) is not complete, it's terminating after the first file sometimes. I'll smooth that out once the server side of the library is together and testing can be self-contained.
I'd like to work on the server library sometime next week, but I'm pretty busy. Is there a better place to contact you with updates?
What do you think? In the mean time we can build some prototypes on different platforms.
The real reason why we don't know how and if this interaction model would work in practice - is the obvious absence of implementations.
A Lua client library for libixp should be pretty straightforward, looking at the source for ixpc. I might have that together this afternoon (particularly if my fiancee continues napping ;) ).
As for a server library, I'm still thinking about it, but passing an init function a table with callbacks for the various messages would be pretty straightforward - similar to LuaExpat's design (http://www.keplerproject.org/luaexpat/manual.html).
I'm silentbicycle on twitter, FWIW.