Okay my last comment wasn't quite correct. Of cource UTC is correctly set to "yes" when os-prober indicates that Ubuntu is the only operating system. So the thing with the wrong time might really be a VirtualBox bug.
Now here is something interesting, I tried this out with Jaunty.
I realised that the underlying problem exists there, too. The filesystem has a last mount time in the future, just as with Karmic. But Jaunty doesn't seem to check whether the last mount time is in the future. (or automatically corrects it, I don't know exactly)
Okay my last comment wasn't quite correct. Of cource UTC is correctly set to "yes" when os-prober indicates that Ubuntu is the only operating system. So the thing with the wrong time might really be a VirtualBox bug.
Now here is something interesting, I tried this out with Jaunty.
I realised that the underlying problem exists there, too. The filesystem has a last mount time in the future, just as with Karmic. But Jaunty doesn't seem to check whether the last mount time is in the future. (or automatically corrects it, I don't know exactly)