In the new Arduino boards, the traditional FTDI USB-to-serial chip has been replaced with an Atmel ATmega8U2 chip, which has built-in USB. We'd like to do the same on the next APM board, and use this chip to do double-duty: replace the FTDI chip that's now on the IMU shield, and replace the PPM encoder chip (now an Atmega328) that's on the APM board. This will make smaller, simpler, cheaper APM boards for all going forward. And bye-bye FTDI drivers!
There should be enough memory in the Atmega8U2 for both the OptiBoot bootloader and the PPM encoder code. But we need some help in combining them in a way that each won't interfere with the other. We've got a lot of great programmers here at DIY Drones. Who's up for the challenge? (Free boards for any volunteers)
Here are some starting links.