OK, this thread needs some images (specially from the M8)...
Yes, as previous posters have mentioned, the high ISO capabilities of the D3 are amazing, but the M8 is not as bad as people say.
While the D3 does give you the ability to shoot at ISO 25,000 with a 1.4 Nikon lens, in those instances where the light is so bad that your shutter speeds are 1/20s, your images are going to be cr*p anyway and I'd rather use a flash regardless of the tool I may be wielding at the moment. Please don't take my comments the wrong way and turn the thread into a big argument as I am not knocking the D3 (like I said it is a great camera I also own but only gets used for macro work on baby portraits).
As always, below is some of my work (fresh from this Saturday's amazing wedding). They were all shot with the M8 and Noctilux, ISO 640, f/1 @1/30s... Please keep in mind that these were shot at the after party (past midnight) and these folks have been having a blast at the open bar and dancing for a while (hint, hint, no static images here). Of course, by no means I am implying they are perfect or everybody's cup of tea, just showing how I use the M8 to pay the bills.
Cheers,