Nielson recently stated that he thinks we should keep building a mobile version of a site that is trimmed down and optimized for mobile, and a full version. This contradicts the growing momentum in the industry regarding among other things Responsive Web Design. Josh Clark, another expert in Mobile and Usability, correctly dissects Nielson's stance and explains why he's seeing things backwards in this article at Net Mag.
Nielsen is wrong on mobile | Opinion | .net magazine
Designer, developer and mobile maven Josh Clark tells us that rather than stripping down, we should be asking how we can do more with the mobile experience