|Just did a dist-upgrade after installing nvidia-drivers from experimental, everything works so far.
However, the new version of Grub does now paint the menu on a black background. I can see that it recognizes the image, as the 10 px border, which was black in Grub 1.98, now shows the specified image. The rest of the image however is completely obscured. Here's my /usr/share/desktop-base/grub-background.sh:
On an unrelated note, bash completion seems messed up, it now inserts a whitespace after a directory, not only after files.