For those who use VirtualBox and also use Rawhide, you might have come across the problem that VirtualBox stopped working with the 2.6.27 kernel. According to the VBox website, the latest 1.6.4 supports the 2.6.27 kernel, but this seems to be incorrect.
A fairly simple fix has been found and documented on Ubuntu forums. So, for those of you using Vbox on Rawhide, here's the link.
It seems to work for just about everyone. (The first post is the one with the solution, most of the others, such as my own, are simple thank you posts.)