Industrial robots, or more appropriately "immovable robotic arms" have been around for decades, and they do things like spot weld cars, paint refrigerators, and check for irregularities in assembly lines.  They are used in a number of different manufacturing sectors, but primarily in the automotive industry and to a lessor extent the electronics industry. Industrial robotics shipments actually sagged between 2000 and 2005--primarily due to the downturn in the automotive industry--while the entire robotic industry almost doubled sales from $5.7 to $11 billion. 
Recent growth in the robotics industry came primarily from the other two robotics segments, which are often lumped together under a category called "mobile robotics." Mobile robotics has technology built into them that allow autonomous movement and interaction with humans and other robots, among other "intelligent" features.
Personal Robots are generally purchased by individual buyers (consumers) and are used to educate, entertain or assist in the home. This market is typified by products such as robotic vacuum cleaners, lawn mowers, and toys, as well as robots that assist the disabled and elderly in the home.
Service robots are semi or fully autonomous mobile robots that assist humans, service equipment and perform other autonomous functions. . They are best utilized for tasks that are repetitive, require continuously high levels of concentration, are physically demanding, or take place in dangerous environments. Robots that perform functions underwater, those that clean, and those that perform precise medical maneuvers are popular examples of service robots.
Probably the largest subclass of service robots is in the defense industry. Unmanned vehicles on the ground, under water, or in the air all fit within this category. Often linked to military robots are search and rescue, fire fighting, de-mining, surveillance and other types of public safety robots.
General Dynamics (GD) and Lockheed Martin (LMT) are two examples of major military vendors currently working on unmanned robotics that should benefit from increased military contracts for unmanned vehicles. Although much smaller, IRobot (IRBT) is a pure-play robotics company with 40% of its sales from military contracts (and as a company has experience a compound annual growth rate of 62% between 2003-2005. AeroVironment (AVAV) is also a smaller player developing unmanned vehicles for the government. In these turbulent times, demand for defense-related service robotics is predicted to be very strong.
Electrolux (ELUXY), Samsung, and LG are all large home appliance manufacturers that are working on or offering personal robot products. Given that iRobot's flagship "Roomba" robot floor vacuum, introduced in 2002, already commands a 3% market share out of the $3.4 billion vacuum cleaner market, demand for these products seems real.
Fanuc and Yaskawa Electric are some of the largest industrial robotics manufacturers in the world. Although their growth rates are smaller due to market maturity, demand for industrial robots among many manufacturing sectors is still consistent, and may grow due to technology enhancements made throughout the robotics industry. in the 3rd quarter of 2007, Yaskawa reported that 70% of its robotics sales came from the automotive industry, showing a strong dependence on that industry.
The War on Terror has increased federal spending on defense both at home and abroad. In an effort to save costs and human lives, Congress is pushing defense dollars towards unmanned vehicles and thus the robotics industry. In fact, the U.S. Defense Department released a 25 year road map for unmanned aerial vehicles in 2003 which called for an increase of spending on these machines 3-fold to $10B in 2010. .
As the main drivers of industrial robotics sales, which still comprise about half of total industry sales, the health of the automobile and to a lessor extent the electronics industry is correlated to the health of the robotics industry.
The main limiting factor to the growth of the robotics field is technology. Some of the toughest problems of robotics, such as visual recognition, navigation and machine learning, once understood, will propel the robotics field further into the mainstream instead of just niche market where it mainly resides today. Bill Gates, in a recent article published in Scientific American , compared the robotics industry to the emerging PC industry 30 years ago when computer mainframes were mainly used in niche markets. He predicted that the future would see robots as ubiquitous as PCs, assuming that programming standards were set in place so programmers wouldn't have to start from scratch with each new robotic application.