The November 26, 2007 issue of the Economist includes an article offering a good overview of nanotech as an environmental issue.   The article notes that very few nanotech materials have been tested for human health or environmental impacts, and that what we know about much larger units of various materials provides no guidance for predicting the impacts of small particles of those materials.  Indeed, the unusual properties of nano-materials are partly why they are so potentially useful.  

Also this week, a study published in the journal Nature Nanotechnology (look under the heading, Public Perceptions) indicate that the general public is much less aware of the risks of nanotechnology than the scientists who are experts in the field.   The study is available only to subscribers, but Science Daily and Agence France-Presse have helpful coverage.