RewriteEngine on

 # test if rewrite should stop for
 # special directories
 RewriteRule ^(favicon.ico|robots.txt) - [L]
 RewriteRule ^(images|skins|auto|files|stats)/.*/? - [L]
 # all php scripts.
 RewriteRule \.php$ - [L]

 # do the rewrite
 RewriteRule ^wiki/?(.*)$ /index.php?title=$1 [L,QSA]
 RewriteRule ^/?(.*)$ /index.php?title=$1 [L,QSA]