I vaguely remember hearing the descent engines in the sky crane of curiosity were monopropellants and ran on hydrazine. Is this true and is there any other information on the engines available?
That's correct, they're hydrazine monopropellant thrusters.
Each rocket thruster, called a Mars Lander Engine (MLE), produces 400 to 3,100 N (90 to 697 lbf) of thrust and were derived from those used on the Viking landers.
The citation links to an Aerojet press release which contains a little more information:
After deployment of a parachute, MSL will perform final descent to near the Martian surface using its eight Aerojet 700-pound thrust engines.
Aerojet's model number for these thrusters is MR-80B. The specs for this thruster (as well as many others) are on a datasheet available from Aerojet. Here's some deeper technical info on the development of the thrusters.