I just want to mention one more thing. The best way to get a feel is to look at the docs (http://kevincox.bitbucket.org/ooarduino/doxygen/) and look around. The most interesting classes are Pin (for digital IO), PwmController and PwmPin (for PWM), BufferedSerial (for easy serial comunications) and Clock/LongClock (for timing).
I plan on adding examples of how to do simple things in the wiki but I don't have time right now. Hopefully in a couple of days I'll have blinking lights and serial communication.