An RPG is basically a bazooka. After 150 yards, you are just spraying and praying.
A friend, who is informed on the weapons used in Iraq, explained that though they look like the sophisticated counterparts, are basically big bottlerockets with big payloads. They do not have the electronics to guide them as the electronics are too expensive to make in quantity in the back yard of some Iraqi/Palestinian home.
However, the sophistication of some of the ways to hide rocket-armed trucks is pretty incredible...imagine a sandwich truck pulling and the GIs think they are getting chow, but instead the doors open and a barrage of rockets at 150 feet begins.