from the Iraqi Casualties Site, the latest entry:
"04/10/04 Centcom: 1 Soldier Killed, 2 Wounded at Balad Air Base. A mortar attack occurred at approximately 12:20 a.m today at Balad Air Base, killing one Airman and injuring two others."
The use of mortars has been increasing - the explosion in the cneter of Iraq yesterday waas also a mortar attack.
One advantage for the attackers using mortars is that they do not give you a direct line back from where they were fired -- it is somewhat more difficult to apply suppressing fire than it would be with RPGs, for example. Also, an experienced mortar operator can fairly quickly get off 3 shots, either bracketing a desired target {short, long, middle}, or "walking" the rounds up, gradually icnreasing the range. So far this has not been being done.
A single mortar round is not necessarily going to be all that accurate, unless when has a fairly good estimation of the range, and also relatively calm wind conditions. Still, the fact the mortars are being seen somewhat more frequently and that they are increasingly being used against fixed target 0such as barracks and police stations) increases the possibility of serious casualties.