Various LightWare devices already have support in the current 3.3.3 release of ArduCopter. Most devices will work with the serial interface, and all of them support the analog interface.
I2C support is only available on the development version of ArduCopter.
Unfortunately rangefinders in ArduCopter don’t work in auto-mode. I am currently researching this and don’t have an exact time-frame of when we will have an implementation. I’ll probably have more info next week.