Available now via Canon Japan's website, the firmware updates add support for the AF assist beam feature of the new Speedlite 270EX flash, which is scheduled to be released this month.
The Canon EOS 50D update also "addresses the vertical banding noise phenomenon" and "changes the error indications that are displayed on the camera", according to the company.
Click the links below for more info, downloads and instructions:
Canon EOS 50D firmware v1.0.6
Canon EOS Rebel XSi / 450D firmware v1.1.0
Canon EOS Rebel XS / 1000D firmware v1.0.5