I just pushed initial support for atmega32u4 and improved support for at90usb1286 MCUs to AVR-Ada repository. This means you can now use AVR-Ada with your teensy and Arduino Leonardo devices.
Teensy 2.0, Arduino Leonardo, and Arduino Micro devices have atmega32u4 processor and teensy++ 2.0 has at90usb1286 processor. These processors have USB functionality built in the processor itself, so in theory you can let them simulate USB keyboards, mouses, and other devices relatively easily. However, AVR-Ada itself does not contain any USB code yet, so you are expected to do everything from scratch by yourself.
In addition, I also pushed some USI code for attiny processors and now you can use attiny2313 or attiny4313 as I2C master.