The United States armed forces are getting to use their new capabilities to the fullest in the Falluja assault. Networked units, night-vision capability, close air and artillery support are flattening the irregular forces who have no good way to defend against the punishing firepower.
US troops are much safer now as well, thanks to the next generation of Kevlar and ceramic technology found in the new Interceptor Vests, the first body armor capable of stopping a 7.62mm round (used by the AK-47, AK-74, and many types of heavy machine guns favored by guerrilla and terror groups because they are cheap and plentiful).
A friend of mine noted that the present trend in military weapons manufacturing is to develop rounds with less and less power. He theorized that this was to ensure that the advantage stays with the side with the body armor, which is prohibitively expensive for guerrilla-type organizations. (The Interceptor costs over a thousand dollars, while the AK-47 can be bought in some areas of Iraq for less than a hundred.) At the moment, there are some rounds that can still penetrate body armor. These include hunting rounds like the 30-.06, and the .50 Barrett round; but both of these are expensive, and neither of them can produce fully-automatic fire, a necessity against a regular army.
In short, the irregular enemies of the modern army are overwhelmingly outgunned, and are much less capable of injuring their target.
How do they adjust? When possible, they attack easier targets such as the Iraqi police or National Guard, who are not as well equipped as American forces. This is a temporary situation, however, and in any event it does not prevent American troops from counterattacking. Irregulars also rely heavily on roadside bombs and other types of explosives, but the roads are coming under increasing surveillance, making it harder to plant the bombs safely. Moreover, the same advanced Kevlar is now armoring American Humvees and other vehicles, reducing the bombs' effectiveness.
It seems that the weapons-balance has returned to the days of the armored knight, pre-longbow. The army with the greatest budget and support structure is unstoppable.
Of course, nothing will stop the enemy from developing their own capabilities. Hizbullah apparently has developed an unmanned aerial drone, which flew over the Lebanese border a few days ago…
[UPDATE: I have been informed that there are indeed 30-06 and .50 rifles capable of automatic fire. But they remain much less common than the AK family of assault-rifles.]