From Breeze Systems:
PSRemote is an application for controlling Canon PowerShot cameras from a Windows PC. It gives a high degree of control over the camera and includes a live viewfinder display allowing the camera to be operated up to 5m (16 feet) from the computer using a standard USB cable. PSRemote is designed for all Canon PowerShot cameras that support remote capture including the G10, G9, G7, SX110 IS, SX100 IS, S5 IS, A640, S80, Pro1, G6, S3 IS, S2 IS, S70, A620, A520, and many other cameras. PSRemote enables Canon PowerShot camera users to operate the camera from a distance and in inaccessible locations, see live viewfinder display on PC screen, gain unrivalled control of camera settings in tethered operation, and create time lapse sequences over short or extended periods.