See related story: Robot Vacs Are in the House

Available in Europe for about 1,100 euros, or $1,300, the Kärcher RoboCleaner is approximately 11 inches in diameter and about 4 inches tall.
Kärcher
The $1,700 Trilobite creates an internal map of the room as it cleans, and automatically recharges when it runs out of juice. It navigates by ultrasound, but needs magnetic strips to tell it about doorways and stairs.
Electrolux
Currently in home trials, Dyson's DCO6 robotic vacuum cleaner is designed to clean efficiently and without needing to be programmed.
Dyson
Hitachi's robot vacuum is a domestic drudge with a twist -- it doubles as a digital watchdog.
Hitachi