@Graw: if you need RAW I will make it (we are talking about BASIC support; in application mode you program W5100 directly).
@edoz: we are talking about BASIC device names - OPEN"TCP2B:"FOR INPUT AS#1. I do not need so many socket connections - you as programmer may need. If you personally do not need it does not mean everyone else does not 
Thus I am targeting for maximum configuration for all of you.
Sockets only apply to the built-in TCP/IP stack. If the ethernet frames can be accessed directly, there is no limit to how many sockets can be created, at least not a hardware one, at the cost of some additional CPU processing cost (similar to Obsonet).
The way I’m thinking is, once one would need an additional socket beyond the 4th, in stead of plugging in another GR8NET, it could just create additional software sockets without hardware acceleration. If the W5100 permits bypassing the TCP/IP stack, that is.
I think from a hardware point of view it will be possible. But I'm not totally sure. I think this because konamiman created 2 rom flash files in the past for the denyonet. One for running the stack on the chip and one on the device itself. In the end if you want to run more sockets at once it would be better maybe to have 2 network adapters as it will perform better I think .. Especially when you need a lot of sockets for your software 
at least it would look much cooler if you attach 8 network cards to your MSX 
Cool, keep us updated!
@Prodatron Good to know!