I did post this link few days ago, but here are the actual concept sketches and appropriate discussions which I find very interesting. I hope Leica AG has already looked into that, since there are some interesting suggestions (like the AE-L lock button):
Here is the first Leica M9 sketch (discussion):
and the more "traditional" approach:
Disclaimer: those sketches were done by a Leica fan and may not reflect any future M model.