"I would bet my Nikon it would not be possible to tell a Large format scan and a pic from a Canon 1Ds in a jpg at that resolution as far as detail and tone goes."
Here's an old comparison
http://www.luminous-landscape.com/reviews/shootout.shtml
While I disagree with Pete that you can't get the quality with digital, it seems prohibitively costly and arduous for all but the most moneyed photographers to shoot in the field with medium format digital. I was at the Focus show at the NEC this week, the 22mp digital backs are stunning slapped on a Hasselblad, nice at 16000 quid...
At work we have a drum scanner and scan 6 x 6's all the time so trust me I know my stuff. Now the Phase One stuff, in contrast, has no grain or dust...
But I like grain and dust!