It does kind of depend on the details of what Arm platform, what Digispark libraries, etc. If the Digispark libraries used are the standard Arduino libraries, then if you use an Arm chip that uses an Arduino interface, they may work without change. Libraries that know about the low level details of the architecture (using PROGMEM, PORT macros for instance) will likely have to be changed. For example, the Arduino Due or the Teensy 3.0 are both Arm chips that use the Arduino IDE to do their programming. I can move stuff between my Arduino and my Teensy 3.0 without change except for pin assignments. I had some issues with Digispark and Fedora 17 and can't yet use my Digisparks, but I hope to get some time to upgrade to Fedora 18 (I think the modem manager holds the USB serial port open too long and the DS software can't run until the DS has timed out -- with Fedora 18, I believe I can eliminate the package in question).