Most of Arduino ATmega boards are supported if you just have Arduino IDE installed.
Teensy 2.x are supported via Teensyduino — Patch for Arduino IDE. You can follow instruction on PJRC site to add Teensy support.
ATtiny boards — not tested yet
ATtiny boards is supported by third party hardware spec.
You can use guide to add ATtiny platform.
ATtiny projects links:
DigiSpark by DigiStump — not tested yet, board on way
DigiSpark is very small ATtiny board. DigiStump team released it’s own Arduino IDE clone for DigiSpark boards.
- add tools
SAM (ARM architecture boards)
Arduino Due is tested, works fine.