I'm afraid that I haven't been able to release it yet. Sorry about that. I've been a bit ill and real life had me working on other things.
It's approaching completion, though. The main functionality is already there - only secondary stuff is left (for example, callbacks are not invoked when popAllStates is called; isInState isn't implemented, and states are not included in mixins - althought I might leave that one out)
As a side note, I've decided that from now on it will be my policy to not provide a folder, but a self-contained file for all my libs. This way you will not need a require 'stateful.stateful' (which in some cases gives trouble to physfs) but simply require 'stateful'.
Regards, and apologies for the delay!
When I write def I mean function.