Hi,
Yesterday I managed to make it work.
Your shield only support 9600 bps and 19200 bps with my Arduino R2. I had to change the baudrate on the shield side to 9600 bps (and then 19200 bps) to be able to cleanly receive characters. With any other higher baudrate, the problem is back.
Yuriq, can you test one more time with an Arduino R2 this time, maybe there is some kind of problem with the previous arduino revision ?
Cedric