The SICK LMS 291 is the latest variant of SICK "coffee-pot" laser rangefinders, which comes in a characteristic beige color. The SICK LMS 291 costs approximately $6000 and sports a 75 Hz scan rate over 180° range, with 0.25° angular resolution. Their sensing range is 30 meters (at 10% reflectivity, max range of 80 meters), with an error of about 10mm. Thanks to a rugged metal housing, the LMS 291 is rather bulky (18.5 x 15.6 x 21.0 cm), weighing in at approximately 4.5kg. They require approximately 20 Watts of power, operating off on a 24VDC supply.
The SICK LMS 291 relies on a spinning mirror and laser diode to perform time-of-flight distance calculations. In a tear-down of the laser rangefinder, one can clearly see the main components, such as the spinning mirror mechanism, laser diodes, etc. (more on this blog entry).
While these laser rangefinders feature predominantly in industrial (safety) operations, they have also become fixtures on many robots -- for both SLAM applications (below left) and as a "sweeping" sensors for safety and perception (below right).
It is my belief that the SICK LMS 291 model will be outmoded for most robotics applications by the SICK LMS 100 (which is smaller and has lower power requirements), the Ibeo line of laser rangefinders (which was designed for seamless integration with robot vehicles and is a subsidiary of SICK), or one of the other competing LIDAR variants (such as the small Hokuyo laser rangefinders that are becoming ubiquitous in robotics).
Detailed specifications for the SICK LMS 291 can be found in this PDF document.