We are just finalising the design of our 24 Channel Servo Control SplashBridge.
Were using an LPC11U24, it has a built in USB Stack in ROM with a Mass storage device bootloader so updating code it as easy and dragging a hex file into a removable drive. The Cortex M0 will be controlled either via USB (HID or CDC) or SPI. We have allowed up to 5 chip select lines so that these boards can be stacked. This means you *could* control up to 120 servo's. This board also plugs in to our SplashBase board which then allows you to control the servo's via your network.
I've posted a blog entry up here : http://www.soldersplash.co.uk/2012/11/2 ... ontroller/
Let me know what you think!