arduino 0023 + ubuntu 12.04

It's not a bug.

Does the arduino show up in /dev? With what permissions? Did you follow the instructions?

groups | grep "$(ls -l /dev/ttyACM* | awk '{print $4}')" > /dev/null && echo "Permissions correct"

does that print out "Permissions correct"? What's the output of

ls -l /dev/ttyACM*

and

groups