There have been some great posts/discussions at the blog The Online Photographer in the last week about this, proximately prompted by the new Fuji digital rangefinder just announced at Photokina:

http://theonlinephotographer.typepad.com/the_online_photogra...

http://theonlinephotographer.typepad.com/the_online_photogra...

http://theonlinephotographer.typepad.com/the_online_photogra...

and then less directly:

http://theonlinephotographer.typepad.com/the_online_photogra...