I mentioned this in another thread. (The thread about developing a client for iOS or Android.) I'll give a quick rundown of what I'm thinking here.
The basic concept is to document the client and the server interfaces so that anyone wishing to create a client from scratch can. I'm not aware of any reason that the client has to be in Java using JOGL and AWT. (I could be wrong. There could be procedures that just aren't practical to do without these. Haven't dug into the code enough myself.) If the interfaces are implemented correctly, it should be possible to do the client in Objective C, C#, etc.
However, I think it's going to be a relatively large task that is likely going to need some active community support and not just a single person project. Interfaces are likely to change as bugs are fixed and new content is released. It's not something I'm willing to tackle alone if there isn't going to be anyone else to support it down the road. I also don't want to start something like this without J&L at least saying they don't mind.
I guess my only questions then are:
1. Is there any interest in this whatsoever?
2. Is there anyone willing to help maintain something like this (assuming there is anyone out there with the desire to recreate a client for a platform HnH isn't supported on)?
3. Where should the project be hosted at? My only two thoughts would be Google Docs or a wiki. (RoB wiki maybe?)
I'm sure several people already have some notes on the client code already if they are willing to share.