$page==0 or $is_front

If you plan to use $is_front for to check whether or not to display a node, here is a good thread (especially read the comments) that discusses the difference between using the $page and $is_front variables.

Simply put $is_front is set ONLY when you are on the front page of the site. The $is_front variable is NOT set for "listing" pages, e.g. if you click on a taxonomy term and get a listing of nodes classified under that taxonomy term.

$page is equal to 0 for all "listing" pages (including nodes classified under a specific taxonomy term, etc.)