This is probably the same thing as the plug-in extensibility architecture you have been talking about. But, just in case that might not cover this application...

Specifically, I'd like to use the existing Venstar Thermostat GUI Device interface with my Proliphix Thermostat. The Proliphix tstats have equivalent functions for all of the supported Venstar functions. The only real difference is that the communications with the Proliphix are via TCP/IP instead of Insteon. So, if there were some abstraction layer between the GUI presentation and the actual server I/O... well, that would be great.

I can also think of other applications with similar mapability: EZIO to Phidgets is one.