Now that it's almost 2008, I'm giving serious consideration to installing several hundred AFCIs in the coming months. I had a thought that it might not be a code violation to tie the two ungrounded conductors of a MWBC (anywhere but on the breaker itself) and terminate it on one AFCI breaker. In my rather small home these two 15-amp circuits are 18 receptacles and lights, including a bath GFCI receptacle.
Dave
