Canon has released firmware updates for its 50D, 450D and 1000D digital SLRs. Firmware versions 1.0.6, 1.1.0 and 1.0.5 for EOS 50D, Rebel XSi (450D) and Rebel XS (1000D) respectively, support the AF assist beam feature of Canon's latest Speedlight 270 EX flashgun. Additionally, the 50D update rectifies other issues including vertical banding noise.
EOS 50D users are also advised to update the Digital Photo Professional, Picture Style Editor, ZoomBrowser EX and ImageBrowser software to the latest versions.
50D:
http://web.canon.jp/imaging/eosd/fir.../firmware.html
450D:
http://web.canon.jp/imaging/eosd/fir.../firmware.html
1000D:
http://web.canon.jp/imaging/eosd/fir.../firmware.html