Canon has released its latest firmware update for the EOS 7D. The update eliminates the latent image problem mentioned in the service notice dated 10/27/09. This is firmware V1.1.0 and can be applied to cameras with firmware 1.0.9.
Follow the link for instructions and the firmware download:
Canon has issued a service statement for the Canon 7D HERE
In images captured by continuous shooting, and under certain conditions, barely noticeable traces of the immediately preceding frame may be visible. This phenomenon is not noticeable in an image with optimal exposure. The phenomenon may become more noticeable if a retouching process such as level compensation is applied to emphasize the image.