KDE 4.8.1 update: kwin crashing

[Patrick O'Callaghan]

Last night I noticed a lot of 4.8.* rpms in updates-testing, so I
decided to have go:

sudo yum --enablerepo=updates-testing update "KDE Software Compilation"

Now I find that Kwin crashes on login, leaving me without a window
manager, and hence unable even to focus on a console window. Kwin is
from kde-workspace-4.8.1-2.fc16.x86_64. The problem occurs even when I
rename .kde and try again.

Writing this from FVWM (which is very functional and fast BTW :-)

poc