One of the main problems in delivering high technical quality images to the market has been the cost of suitable digital cameras.
Affordability has been pretty poor in the last few years but with the resourgence of competition between Nikon and Canon nobody should be very far away from at least 12megapixel bodies which I consider to be the minimum requirement for high end stock.
Canon today released details of the 5D MKII which with 21mp and a price of £2300 means that anyone earning a reasonable amount from stock can up the quality of their shots and potentially get sales from bigger (and better) repro uses.
It goes without saying that technical quality isnt the end of the story, but I have retouched too many fantastic images that were too small for even full page use….
http://www.dpreview.com/news/0809/08091705canon_5dmarkII.asp