The Pi-Pan has two major parts, software and hardware.
For software, it uses ServoBlaster - https://github.com/richardghirst/PiBits. We will release the software as soon as it's ready, it will be a source code patch file with any enhancements that our engineers are working on.
We will also have a pre-compiled download to simplify installation.
Hardware is extensible by design. To start with it will have two servo headers (for Pan and Tilt servos), but the board has provision for 6 servos. By soldering additional pins on the board, you will be able to add more servos, (You can use the board for things other than just Pan-Tilt).
The board will also have I2C pins, (where Pi-Light connects).
You can simply connect Pi-Light on it, or use that I2C interface for other smart devices!
The hardware design is still being worked on (the actual production board will be slightly smaller than the prototype version we have currently). We will be releasing the schematic on our website when it's finalized.