The Arduino software comes with a number of excellent examples for communicating with Processing and Max/MSP. This is an attempt to make available code for other desktop environments. Currently I have some examples for Pure Data, OpenFrameworks, and Max 4.6.
With Pure Data, I'm building patches using Hans Steiner's recent PD-Extended builds, as they rely on the GEM and moocow libraries (among others).
I'd like to continue working on this, eventually adding standardized examples for Python, Cinder, and AS3. If you'd like to lend a hand or have suggestions for improvements please let me know.