http://www.thunderbolts.info/wp/2011/10 ... -machines/
Trying to have Curiosity lowered to the surface from a hovering decent craft seems extremely dangerous to the mission. The article says that the mission scientists are worried about incinerating potential life at the landing site. Curiosity, however, is a Rover... this seems like an unnecessary risk for a vehicle that can just cruise a few yards over and start searching for life away from any region that may have been affected by its descent.