This firmware update (Version 2.0.7) incorporates the following improvements and fixes.
Fixes a phenomenon in which the aperture exhibits abnormal movement when shooting movies in manual exposure mode and Aperture Priority AE (Av mode) using some Canon lenses (such as macro lenses).
Fixes a phenomenon in which the exposure level shown in the LCD panel differs from what is shown in the viewfinder when shooting still images in manual exposure mode.
Fixes a phenomenon in which the Wireless File Transmitter (WFT-E4 or WFT-E4 II) may not automatically power off when used for FTP transfers.
These phenomenon only occur with the Version 2.0.4 and Version 2.0.3 firmware.
The Version 2.0.7 firmware being released this time is for cameras with firmware up to Version 2.0.4. If the camera's firmware is already Version 2.0.7, it is not necessary to update the firmware.
(Photo credit: snap from the canon site)