Could it be possible to jam i2c through an XBee's digital IO pins?
Say, like, an Arduino's Analog 4&5 pins for i2c's CLK and DAT are punted into two of the XBee's DIO pins. Then, the remote XBee's DIO pins can be plopped into the back of the Adafruit Mini 8x8 LED I2C Backpack along with a battery. I'd imagine on the Arduino side, the XBee would require Adafruit's XBee Adapter kit to step the voltage down.
Can the XBee's DIO pins be twaggled quickly enough to pass i2c wirelessly? Imagining an itty bitty stand-alone battery-powered wireless LED matrix display controlled from a remote Arduino/computer, using XBee's DIO pins as the glue.