I'm looking at the [ATMega328p data sheet][1], and [an Arduino Pin diagram][2], trying to determine if the chip can support three UART connections. I see that PD0 and PD1 are "USART" In and Out. So does that mean the other 10 or so Digital pins can be used for "UART" communications? 

I have a need to connect three UART devices through the ATMega chip. The ATMega will forward traffic between two of the devices at a time, depending on which mode it's in. 

  [1]: http://www.atmel.com/images/atmel-8271-8-bit-avr-microcontroller-atmega48a-48pa-88a-88pa-168a-168pa-328-328p_datasheet_complete.pdf
  [2]: http://arduino.cc/en/Hacking/Atmega168Hardware