Addressing the black dot issue and vertical banding problems that 5D Mark II users have been complaining about, today Canon has released a firmware update to address the issue.
The Firmware and instructions can be found here: Canon EOS 5D MarkII Firmware Update Version 1.0.7
From their web site:
It improves and mitigates the following image quality phenomena:
"Black dot" phenomenon (the right side of point light sources becomes black)
When shooting night scenes, the right side of point light sources (such as lights from building windows) may become black. The phenomenon may become visible if the images are enlarged to 100% or greater on a monitor or if extremely large prints of the images are made. This firmware improves and mitigates this phenomenon.
- Vertical banding noise: If the recording format is set to sRAW1, vertical banding noise may become visible depending on the camera settings, subject, and background. The firmware improves and mitigates this phenomenon.
In addition, the Digital Photo Professional and Picture Style Editor applications have also been updated, again from Canons web site:
If the existing software applications are used to display sRAW1 and sRAW2 images that were captured by a camera with Firmware Version 1.0.7, dark, low-contrast areas in the images may appear slightly magenta. If the updated software applications are used to display sRAW1 and sRAW2 images, the color of the images will appear normal, regardless of the camera firmware version.