Seems that I was wrong and Brian Eaton <eaton.lists@gmail.com> was right:
default apache installations seem to return an explicit charset in their
error message. (Now I cannot explain how I convinced myself otherwise.)
Then there is no Universal XSS against default Apache webservers...

Cheers,

Paul Szabo psz@maths.usyd.edu.au http://www.maths.usyd.edu.au/u/psz/
School of Mathematics and Statistics University of Sydney Australia