Here is an interesting experiment with soluble 3d print support material. Support material used is HIPS (High Impact Polystyrene) in combination to support ABS. HIPS is soluble in Limonene (4-isopropenyl-1-methylcyclohexene). The results look pretty good.
More details on:
http://www.3dppvd.org/wp/2013/02/soluble-support-material/
More details on:
http://www.3dppvd.org/wp/2013/02/soluble-support-material/