I'm trying to control a massive array of motorized faders (like these: http://www.alps.com/WebObjects/catalog.woa/E/HTML/Potentiometer/SlidePotentiometers/RSN1M/RSN1M_list.html ).

I'm able to control them manually by reading the analog in from the slide pot and controlling the attached DC motor with a PWM motor controller. This works fine for a few, but when you get up to 100's it starts to get really inefficient.

I'm wondering if a custom servo type IC would be the solution. Something kind of like your motor controller, but with an analog input (for the slide pot) and enough on-board smarts to use a PWM position signal to drive the motor to a specific position - basically turning the whole assembly into a standalone Servo.

Is this something that's possible? If so, our company would use about 500 of them (!)

Perhaps a TLC5940. Here is a Breakout board from Sparkfun and a tutorial from bildr.org. Here is some additional information and Arduino Libraries.

Or perhaps the PCA9685. Here is the Adafruit 16-Channel 12-bit PWM/Servo Driver - I2C interface which uses it. You can even chain up 62 breakouts to control up to 992 PWM outputs! Here is a tutorial and Arduino Library.