I actually work with most of the major footwear companies in the country (I work at Material ConneXion), and most of them (finally!) are really concerned about sustainability and ask me regularly about eco-friendly footwear materials. It is very encouraging.
Nike has really led the pack, they have a person who works in their material library who ONLY looks at eco-friendly materials. And I think Nikegrind is great. My opinion of Nike (including business practices, ethics, etc) has changed dramatically over the last year or two… they (and the footwear industry as a whole) have a long way to go, but it is impressive that such a large company has made such fundamental changes in a short amount of time.