The Teensy 3.0 is now entering general release if you wanted an ARM board in a smaller package than the DUE. The Teensy is not the DUE, so be sure to understand what it offers and what it doesn't. Teensy 3.0 uses a modified Arduino 1.0.1 IDE.
- PJRC Store - Pjrc.com store
- http://www.pjrc.com/teensy/beta/ - Download software