Nine years of war have changed attitudes on how to equip and use armored vehicles. Thus the proliferation of remote control (from inside the vehicle) machine-gun turrets, all-around sensors (including night vision and thermals) and anti-sniper and anti-missile systems. Armored vehicle design has changed considerably in the last decade, and it's largely due to new technology, and new needs.
Since 2001, most of the combat has been against irregulars, whose only effective weapon is the anti-vehicle mine and roadside bomb. While the M-1 tank was pretty resistant to these weapons, smaller armored vehicles were not. Thus the proliferation of the MRAP vehicles, and armor kits for hummers and trucks.
The mines and bombs were not all that effective, but got a lot of publicity because they were the most common source of American combat deaths. Compared to Vietnam or World War II, U.S. troops in Iraq were only a third as likely to be killed. The death rate in Afghanistan was even lower. The troops noted the lower casualty rate, and changed their tactics accordingly.
There haven't been any other tanks to shoot at since 2003, but there have been plenty of RPGs (rocket propelled grenades, a cheap and effective weapon developed late in World War II). M-1 tanks are largely immune to RPGs, but all lesser armored vehicles are not. The U.S. adapted new types of armor (reactive, stand-off, composite) to make lighter armored vehicles less vulnerable to RPGs, and this generally worked (as in, there were few RPG caused casualties in these vehicles.)
Even the M-1 tank got a makeover. Over the last five years, the U.S. Army has been expanding and improving the TUSK (Tank Urban Survival Kit) program. The kit is a collection of additional features for M-1 tanks, which make them more effective when fighting in urban areas. The upgrades include the "loaders' armor gun shields," which is transparent ballistic glass, so the loader doesn't have his vision blocked. This is important for street fighting. The loaders machine-gun is now equipped with a thermal sight, making it more deadly at night. There is also a .50 caliber machine-gun being mounted on the main gun, so the 120mm fire control system can be used to fire the machine-gun, instead of 120mm shells.
Other components of TUSK are reactive armor panels for the side and rear of the tank, to provide added protection from RPGs. A slat armor panel protects the engine exhaust outlet of the tank from RPGs. A 1.5 ton belly armor kit, which can be installed in two hours, provides additional protection from mines and large bombs. Enhancements also include night vision for all crew members. There is also a telephone added to the side of the tank, so that infantry can more easily communicate with the crew when the tank is "buttoned up" (all hatches closed). The complete TUSK kit costs close to a million dollars now, and takes about twelve hours to install all the components.
Recently added TUSK items include, a rear-view camera for the driver and CROWS (including one using thermal imaging), a system that allows the commander's .50 caliber machine-gun to be operated remotely, while the tank commander is inside the turret. This is particularly useful if the tank is taking a lot of small arms fire.
New TUSK items in development include sniper detection systems, and special body armor for the crew (that doesnt have to be worn inside the tank, where conditions are cramped, but can be quickly slipped on if you have to get outside in a hurry). New crew uniforms are in development, that are more fire resistant. Internal communications are being modified so that a wireless link takes over if the hardwire one gets disconnected. There are more types of computers and displays under development. Waiting in the wings (for wider adoption) are anti-missile systems (for the kind of anti-tank guided missiles that most Islamic terrorists cannot afford.)
TUSK was first proposed five years ago, and kits began arriving in Iraq three years ago. Most TUSK items are showing up in other armored vehicles, and fundamentally changing armored vehicle design philosophies. The main problem now is that thirty year old designs, loaded up with more recent technology, are getting the job done. In the past, armored vehicle design was driven by new threats, that made existing vehicles obsolete. That situation does not exist now, and efforts to get money for new designs is difficult.