According to Canon changes in this firmware are:
1. Improves writing/reading speeds when using UDMA _7-compatible CF cards.
2. Fixes a phenomenon where the ability to shoot movies
_may be stopped under the following conditions:
• When using high-capacity (32 GB or greater) CF cards
_with little available space remaining and the user
_attempts to start shooting movies; or
• When the camera’s battery is removed and reinserted
_into the camera and the user immediately attempts to
_start shooting movies.
3. Corrects misspellings in the menu screens displayed in Arabic and Portuguese languages (applies to models outside of the the Japanese market only).
Firmware Version 1.1.0 is for cameras with firmware up to Version 1.0.8. If the camera’s firmware is already Version 1.1.0, it is not necessary to update the firmware.
You can download the firmware from Canon here:
Download for OSX or Windows
Note that cameras with the Version 1.1.0 and Version 1.0.8 firmware cannot be downgraded to a previous firmware version (such as Version 1.0.6 or earlier).
Find a list of all Canon firmware pages and older firmware in this forum topic.