Yes, SIGS and WON are the same thing and they use the same protocol. They seem to have just renamed it at some point to WON. Anyways, I was able to get a login going for WON using my SIGS emulation, but there seems to be a lot more information required and I haven't been able to get as far. (More error, which is why I'm sticking with the older SIGS system for now).
It would be entirely possible to create a chat client that used the SIGS protocol to communicate, or any other that is built into the server, but I haven't even gotten the native SIGS chat part to work. I think any planning for a seperate client, or a link in with IRC is quite far away. Also, I don't see how you can properly link with IRC unless the server software had built in IRC software. I really don't like the idea of wrapping things in script after script and end up having people talk through a bot or something. That just strikes me as way too spamy, and much too hacked of a system. But, I guess we'll see when the time comes where we can start seriously planning something about this.
leeor_net: That interface you see is implemented in the DLL. If you were to link to those DLLs and use them, you'd get the same interface, and of course, the same protocol. Of course, not all the options would then make sense. Like Create Game and Join Game. If you wanted to use the same protocol with a different interface, or a remade interface, you'd be writing all the protocol handing. Of course, the way the protocol is implemented in the original DLLs makes it somewhat easy to reuse code between the client and the server, and I'm developing my code along the same lines. Hopefully it'll be somewhat easy to encapsulate it nicely into a library.
Oh, and if someone remembers a different interface for SIGS/WON, that's highly possible. The interface was implemented by the DLLs, so each new version of the DLLs could mean a new interface. The WON DLLs even appeared somewhat skinable. (I haven't really looked into using them though.)
Btw, for people trying to write a SIGS client using the existing DLLs/interface, I've obtained some info on how the DLL interface is supposed to work and the sort of calls you'd need to make to it. (Granted, the informations is a bit outdated as it was for an early beta, but it's still fairly accurate and potentially quite useful.)
Anyways, as far as a server idea goes, I'm strongly for using the existing protocol. I wouldn't really want to rewrite a custom DLL from scratch with the same interface as the old one.
Oh, and I should ask. What other games used the SIGS/WON system? It might help if I could get various versions of SNWValid.DLL and SierraNW.DLL. Some versions might have more info in the code than others. (Increased error checking is a big plus here).