I've pushed my Beagleboard Python I2C library up to GitHub, along with the sketch I used to create an Arduino I2C slave that drives an LCD. (A slave driver?)
It's in a public repository at email@example.com:romilly/beagleboard-i2c.git
This is alpha code; the API will change; the code may not work and/or may do bad things. Use it at your own risk.
More coming soon. (Stop press: that will include a non-blank README )
If you aren't familiar with Git/GitHub, there is good reference material here.