[Quazal] (formerly ProkSim) has a library, Net-Z, to handled distributed network gaming, heading in the direction described in Fitch's articles. (See Interesting Links under Networking.) They're working on a replacement that is a full game engine, apparently.
DWM (8/17/2002) I took a gander at the white paper available on their site. I like what I found. I had recently been thinking that, in the interest of being able to easily communicate information across the network about objects, it would be very desirable to have an RPC- or IDL-like language for specifying communicating elements. These specifications would be used to generate communications stub code. Turns out that Net-Z does exactly this. Their framework also handles an adaptable form of dead reckoning, as described in some of the articles referenced by our Interesting Links. It's 'adaptable' in that the error thresholds can be adjusted based on distance between objects, which is a very nice way of saving bandwidth by reducing update frequency for far objects. Programmers provide custom code to define all aspects of this; how distance is defined, what the predective algorithms are for dead-reckoning, etc. At the very least, the article gave me a few more architecture ideas.
Since this library is targeted specifically at MMP games, I suspect it ain't cheap. On the other hand, maybe vendors of such wares offer royalty-based licenses. (Which brings to mind one reason for formalizing business arrangements at some point -- our 'company' might have to be able to enter into such agreements.)
Crosbie Fitch himself has reviewed this product [here].