Options +FollowSymLinks
RewriteEngine On

RewriteCond %{HTTP_HOST} ^(.+).site.com$
RewriteRule ^/(.*)$ http://www.site.com/$1 [R=301,NC]

<virtualhost *:80>
  redirect permanent http://www.site.com/
</virtualhost>

<virtualhost *:80>
  servername www.site.ru
  ...
</virtualhost>