However, my panel will still need some kind of processor & storage (some kind of mini computer) in it right? I can't just have a panel with an ethernet plug (if there even is such a thing). The interface can't be fed directly to an orbiter (panel) from the core... correct?
The insteon device you pointed to isn't just a screen, it has processor etc. (According to the page you linked to, it has
Processor: 400MHZ/ 800MMACs High Performance Processor
Memory: 16 Mb RAM, up to 16 Mb Flash
My point was that even if this particular device isn't MCE compatible, there are other, similar devices that are. rperre, for example, referred you to the Mini2440. AFAIK, that doesn't inherantly use POE, but you could use an extractor with it and achieve what you (I think) want.