The U.S. Navy recently tested its Block IV Tomahawk to see how well its two way communications capability would enable it to hit moving targets. The Block IV managed to do so, but not under combat conditions. That is, not with warships using defensive or electronic weapons to shoot down the incoming missile or mislead its guidance system. The recent navy test used a nearby aircraft (which could be a UAV) that was tracking the exact location of the target ship. That could also be done from a space satellite.
The navy is aware of the fact that Tomahawk is not the ideal anti-ship missile. Against modern defenses anti-ship missiles have to move faster than a Tomahawk and be equipped with a better terminal guidance system. The speed problem cannot be fixed, but the Tomahawk could be equipped with a more capable terminal guidance system. That might be able to handle the tracking and targeting systems for gun and missile systems designed to knock down anti-ship missiles when they get close. In any event, Tomahawk Block 4 has a way to go before it is a competitive anti-ship missiles against modern warships.
The U.S. (and other) navy continues to use Tomahawks in combat on a regular bases. The targets tend to be on land and not mobile. Most of these uses are publicized, but some are not. Several hundred Tomahawks were used against Libya in 2011 and that was the last major use.
The Tomahawk was introduced 32 years ago and over 6,000 have been manufactured so far. U.S. Navy has fired over 2,000 in combat and over 500 for training and testing. The U.S. Navy has over 3,000 Tomahawks on its warships or in storage.
The current Tomahawk, the RGM-109E Block 4 Surface Ship Vertical Launched Tomahawk Land Attack Missile weighs 1.2 tons, is six meters (18 feet) long, has a range of 1,600 kilometers, getting there at a speed of 600-900 kilometers an hour, flying at an altitude of 17-32 meters (50-100 feet), and propelled by a jet engine generating only 600 pounds of thrust. Accuracy is on a par with JDAM (10 meters/31 feet). The Block 4 Tomahawk can be reprogrammed in flight to hit another target and carries a vidcam to allow a missile to check on prospective targets.
In 2012 the Block 4s were recently upgraded so that they can hit moving targets. This was for making Tomahawk capable of carrying out some anti-ship missions, although it can also hit moving land targets. The Tomahawk has been a primary land attack weapon for surface ships and submarines since the 1990s. The Block 3 entered service in 1994, but the Block 4 was a big upgrade with the addition of GPS and remote control in flight.
The United States is developing a successor to the Tomahawk cruise missile that will be heavier (2.2 tons), have a longer range (2,000 kilometers), and a larger (one ton) warhead. The new missile will be stealthier and use a combination of guidance and targeting systems (to improve the chances of success). Price will probably be the key factor in whether this new missile ever enters service. The new Cruise Missile XR (for Extended Range) will probably cost at least twice as much as the current Tomahawk. The cruise missile, when it showed up in the 1980s, was one of the first UAVs, it just wasn't reusable. But UAVs that carry bombs and missiles and can be reused are going to provide competition for a new, $3 million, Cruise Missile XR.