Thom Hogan has some interesting observations on Leica in general and the M9 in particular. For example the oft-overlooked limitations in lens range (due to the finder system), and why a BW M9 would be a good idea (hear hear).
(His idea of an electronic viewfinder inside an optical viewfinder though, I don't think can be done.)
I would like a good electronic viewfinder or screen (the Lumix G1's is only the start) which, like an optical viewfinder, showed some of the scenery outside the image proper! Makes it much easier to compose. Don't some high-end video cameras have EVFs like that?
It won't matter if there's vignetting (because the lens only covers the image area well), because you only need it for orientation. And maybe the outer parts of the chip need not have the resolution or quality of the part making the actual image. That may not be possible to build, but then again, it may be possible somehow if somebody starts thinking about it.