Erm, I have to say that I have done the same project a few weeks ago, hahahaha, as its said, "Great minds think alike"
http://wiki.kungfulabs.com/arduino/i2c-wushu
I only had time to add I2C capabilities before starting exams, but now that parsers are fully working it's easy to expand it.
You can dowload the code from Google Code:
http://code.google.com/p/i2c-wushu/
Also, the word 'Wushu' means in Chinese: martial art, hahaha
I might change the name to ArduBus, don't know, wushu seems diffcult to remember.