The U.S. Army is reorganizing its light aviation battalions, by removing some OH-58 helicopters, and adding RQ-7 Shadow UAVs. The new battalions have 29 aircraft, eight of them UAVs. All this is the result of years of experience with the RQ-7, and some tests, using UAVs as scouts for helicopter gunships, or in cooperation with scout helicopters, rather than the traditional scout helicopter (like the OH-58) operating exclusively. The tests were successful, and the army is updating its tactics as well.
In the last five years, scout helicopters have been doing a lot less scouting, having been replaced by Shadow 200 and Raven UAVs. The scout helicopter pilots are relieved at having UAVs take over some of the more dangerous missions. In particular, the scout helicopter pilots are glad to lose the job of going in to "draw enemy fire" (and thus reveal where the enemy is). This sort of thing has gotten a lot of scout helicopter pilots killed. But there are still situations where the superior situational awareness (two pilots with four eyes, four ears and two noses) of humans are preferable. There are some even more basic considerations. The RQ-7 can stay in the air for up to eight hours per sortie, about three times longer than the OH-58.
The army is also equipping some of its AH-64 helicopter gunships with digital communications that enables them to see what the RQ-7s are seeing. The OH-58s often scout for the AH-64s, finding targets. Now the RQ-7s can do it better, by letting the AH-64 pilots see what the RQ-7 has detected. Already being tested are systems that allow the AH-64, or OH-58 pilots to take control of UAVs. Meanwhile, it's expected that the army aviation battalions will gain more UAVs, and lose helicopters.