There has been rumbling of GTK+ being moved to OSX. You can compile programs and have them run native OSX rather than have to boot into an Xwindows session. I can't wait for gkrellm to run native on my dsktop. No more rootles Xdarwin for us. :)
I believe that the displays for the 17" LCD Monitor, and 17" iMac come from different places, and aren't tied that closely together. I don't think that a 22" iMac is really soemthing taht apple is looking into.