Я не поленился сделал виртуальных хост для тестов, прописал днс, положил .htaccess, создал папку img, пложил файл emacs.txt.
Так вот, хер. Реврайт рул рабочий и работает правильно. Вот лог:

78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [test.epicats.com/sid#9ac9e40][rid#9e23c40/initial] 
(3) [perdir /var/
www/vhosts/test/] strip per-dir prefix: /var/www/vhosts/test/img/emacs.txt -> img/emacs.txt
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [test.epicats.com/sid#9ac9e40][rid#9e23c40/initial] 
(3) [perdir /var/
www/vhosts/test/] applying pattern '^(.*)$' to uri 'img/emacs.txt'
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [test.epicats.com/sid#9ac9e40][rid#9e23c40/initial] 
(2) [perdir /var/
www/vhosts/test/] rewrite 'img/emacs.txt' -> 'http://www.test.epicats.com/img/emacs.txt'
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [test.epicats.com/sid#9ac9e40][rid#9e23c40/initial] 
(2) [perdir /var/
www/vhosts/test/] explicitly forcing redirect with http://www.test.epicats.com/img/emacs.txt
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [test.epicats.com/sid#9ac9e40][rid#9e23c40/initial] 
(1) [perdir /var/
www/vhosts/test/] escaping http://www.test.epicats.com/img/emacs.txt for redirect
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [test.epicats.com/sid#9ac9e40][rid#9e23c40/initial] 
(1) [perdir /var/
www/vhosts/test/] redirect to http://www.test.epicats.com/img/emacs.txt [REDIRECT/301]
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [www.test.epicats.com/sid#9ac9e40][rid#9e27c50/initial] 
(3) [perdir /
var/www/vhosts/test/] strip per-dir prefix: /var/www/vhosts/test/img/emacs.txt -> img/emacs.txt
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [www.test.epicats.com/sid#9ac9e40][rid#9e27c50/initial] 
(3) [perdir /
var/www/vhosts/test/] applying pattern '^(.*)$' to uri 'img/emacs.txt'
78.234.200.83 - - [17/Jan/2011:11:44:51 +0100] [www.test.epicats.com/sid#9ac9e40][rid#9e27c50/initial] 
(1) [perdir /
var/www/vhosts/test/] pass through /var/www/vhosts/test/img/emacs.txt

.htaccess:
RewriteEngine on
RewriteCond %{HTTP_HOST} !^www\.test\.epicats\.com$
RewriteRule ^(.*)$ http://www.test.epicats.com/$1 [L,R=301]