Soy Seal (soy based expanding foam in a can)
 

Higgy just sent me this link. I didn't know the soy based expanding foam was available in a can yet. Apparently Home Depot is carrying it now. He also said that up in Canada they are in the process of banning the non-soy based foam due to out gassing. Perhaps Hig can better explain it.

Humphrey House - Green Remodeling of an Arts and Crafts Bungalow: Soy foam in a can!