In Joomla! 1.0.x it was possible to determine if the user was viewing the front page by using code like this:
Determine if user is viewing the front page in Joomla! 1.0.x
<?php if ($option == 'com_frontpage' || $option == '') { echo 'This is the front page'; } ?>
But in Joomla! 1.5.x the com_frontpage component is no longer present. This is how to achieve the same result in Joomla! 1.5.x
Determine if user is viewing the front page in Joomla! 1.5.x
<?php $menu = & JSite::getMenu(); if ($menu->getActive() == $menu->getDefault()) { echo 'This is the front page'; } ?>
This works by checking to see if the current active menu item is the default one.