I can confirm the same issue on Jaunty / 2.6.28-12-generic
[ 2382.703190] type=1503 audit(1242755787.857:15): operation="inode_permission" requested_mask="w::" denied_mask="w::" fsuid=0 name="/dev/ttyUSB0" pid=21252 profile="/usr/sbin/cupsd"
I can confirm the same issue on Jaunty / 2.6.28-12-generic
[ 2382.703190] type=1503 audit(124275578 7.857:15) : operation= "inode_ permission" requested_ mask="w: :" denied_mask="w::" fsuid=0 name="/dev/ttyUSB0" pid=21252 profile= "/usr/sbin/ cupsd"