A recent Wall Street Journal article identified that insurers are beginning to discount premiums for homes built to green standards such as LEED in addition to discounts for drivers of hybrid and fuel-efficient vehicles.
After a bit of digging around, I did find that Fireman's Fund insurance - one of the companies highlighted in the story - does offer discounts in Ohio of 5% on premiums for homes that are LEED or NAHB Green certified. Additionally, they have made provisions for implementing green features in homes that are rebuilt after a fire or other catastrophic event.
Notably, Fireman's Fund focuses on an affluent market, generally of homes in the price range of $600,000 or more. So far, I have been unable to find a "mainstream" insurer (e.g., Allstate, State Farm, etc.) that offers similar discounts. Nevertheless, it's not uncommon for new products to be adopted at the high end then make their way to the mass market. Other insurers are likely to offer incentives in the same way to help distinguish themselves or stay competitive as the products mature.
If you are looking at new construction, or even updating your home to incorporate more energy-efficient features, I recommend checking with your insurance company to see if a discount may be available. I'll also include a list of any insurers I find offering these discounts on the references page of my website at www.EcofficientLiving.com.