The ATMega 128 has multiple serial ports: (RX0,TX0),(RX1,TX1),(RX2,TX2)
Serial.begin(9600) sets up serial communication on (RX0,TX0) at 9600 baud.
So now lets say I want bidirectional communication with another Arduino, as well as writing to a serial LCD. Unless I'm totally stupid (ok, maybe I am anyway), the Serial class object won't address communication on the other serial ports: (RX1,TX1), and (RX2,TX2).
Let's call (RX0,TX0) COM1, and the others COM2, and COM3.
If these were some sort of appropriate DEFINEs, and there was access to the predeclared Serial object's class (lets call it SerialClass), then you could conceivably pass the COM port to the Serial class constructor in order to communicate with the desired devices. Perhaps something like:
SerialClass Serial, myLCD, my328;
Hopefully something like the above approach could utilize the hardware capabilities rather than the extra memory overhead of the SofwareSerial library.
Stop me if I'm making any sense... :-?