Hej Fabian,
the fact is that on the one hand, you could use the pins 0 and 1 as serial I/O if you are not using the communication back to the computer.
On the other hand I have to anticipate that we are working on a Software version of the serial port that would allow you to have serial communication on any pin. This will be ready for Arduino-0004.
I know 
we haven't even release Arduino-0003, but it is going to be out there in more or less a week. And version 4 will be out in a bit more than a month.
/David