I actually have a rather different security problem.  I would like to set up
a non-firewalled wiki but only a certain group should have access.  This may
be for legal reasons, but has been imposed as a requirment that I cannot 
get around.  Anyone know of a wiki that restricts access in such a way? 

    Yes, see Wiki:OrgPatterns which runs in Wiki:FishBowl mode. - ''This may be exactly what I was looking for... thanks!!!''

''Why not use webserver passwords to restrict access? Or do you wish to restrict '''editing''' by a restricted group? -- AnonymousCoward ;)''

Even restricting the editing could be done easily using the security the webserver provides.

''OTOH, few users have ".htaccess" enabled for them, and even fewer have access to the "httpd.conf".''