The Fashion Institute of Technology Museum in NYC is having an Ecofashion exhibit from May through November 2010, and is offering tours with the curators.
I toured the exhibit 2 weeks ago. It features some modern eco-designers such as Edun and Stella McCartney, but also focuses on the history of fashion and its impact on the environment as new dyes and fabrics were developed over time. I like the idea that we may actually culminate in natural fabrics and dyes since, though it may be seen as a step backwards, it is actually a step forward to realize the impacts of our clothing choices on the environment.
See http://fitnyc.edu/3662.asp for tour dates & other details.