It seems that there is no SoftwareSerial library included in the Arduino IDE on the Udoo. Am I missing something?
Sounds right (from memory), the UDOO's included libraries in Arduino IDE are just the 'core' ones. You can easily add any other library of course.
SoftwareSerial is normally included in the standard libraries AFAIK. (see here: http://arduino.cc/en/Reference/Libraries) I couldn't find a download for the library, but I just realized I can copy the code over from my other machine. DOH!