A quick search of the XMega_Manual for TWI and I found
"up to four I2C and SMBUS
compatible two-wire serial interfaces (TWIs);"
Is there an xmega mcu available that has 3 or 4 I2C or TWI connections?
the 2560 board (from adafruit) I am currently using has only 1 at pins 20 and 21.
I do find some two TWI mcu's available
and another reference to 4 TWIhttp://www.atmel.com/products/microcont ... xmega.aspx
High Integration — XMEGA devices integrate AES and DES crypto modules, up to 32 PWM outputs, 8 UART, 4 TWI (I2C) and 4 SPI channels, a CRC generator module, and more.