Does one need a special controller for digital servos or will a standard controller (SSC-II, SSC-12, SSC-32) work?
The SSC-32 is the best servo controller you will find, and it’s only $39.95. It controls digital and analog servos perfectly. Plus the group move is particularly suited for arm control. 
can the SSC-32 be used/implemented in conjunction on a FPGA board?
thanks
Perhaps you could explain what an FPGA board is?
The SSC-32 can communcate with peripherals through RS232 (-12V or 12V) and TTL (0V or 5V) pins.
The RS232 pins are tied into a serial cable connector, and the TTL pins stand alone above the first servo rail terminal.
If your FPGA board has either TTL or RS232 pins available, then it’s possible that they could communicate.
Nick, FPGA == Field Programmable Gate Array. Too many concepts to explain this late at night for me but as a dramatic over simplification think really, really big PAL or GAL. It is sort of like making your own digital ASIC except the “program” gets loaded into its SRAM look up tables from a PROM of some sort everytime you turn on the power. Some of these devices have multiple microcontroller (or microprocessor) “cores” implemented on the same silicon as all the programmable logic as well as PLLs for clock generation, different types of RAM, and programmable interconnect blocks that will interface to many types of logic lines. For example we build a product that uses a Xilinx Virtex Pro2/50 which has 5 power PC cores, 512K of RAM, comes in an 1152 pin ball grid array, and costs over $2200 a pop in low quantity. Roughly 35% of the 1152 pins are some kind of power/ground connection. Heh. 
As for FPGA board, frequently there are evaluation kits for mid to higher end FPGA devices. Sometimes they have microcontroller on board “just” to help make the FPGA operate. Many FPGA devices have I/O pins that can be programmed to interface with anything from good old 5V TTL to LVDS pairs to PECL or NECL signals. Frequently a board will have configuration options that make it easy to pick what you want on each block of I/O pins. When you create the program for one it is a lot like designing and routing a PC board.
The SSC32 has a serial interface, right? So whether it is connected at TTL levels or RS-232 levels the FPGA would have to have available or implement in code some sort of a UART that can send commands to the SSC32. This might be freely available as a reference note or even an open-core type IP. Perhaps if we knew which FPGA and FPGA board you were referring to l33thxr 
we could give you more detailed information.