Is this .htaccess fix required for Google?

Hi All,

This is my first post on this board. I usually hang out on the CommissionJunction board.

Anyhow, while reading an article on Google indexing, it claims I need to do the following to my .htaccess file:

Options +Indexes
Options +FollowSymLinks
RewriteEngine on
RewriteCond %{HTTP_HOST} ^yoursite\.com
RewriteRule ^(.*)$ http://www.yoursite.com/$1 [R=permanent,L]
RewriteBase /
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_URI} !(.*)/$
RewriteRule ^(.*)$ http://www.yoursite.com/$1/ [L,R=301]

Code (markup):

Otherwise, google will think there are 4 versions of the site: with/without trailing slash and with/without "www"

Is this true?