If you want to add the page number into the title of your blog just copy-paste the following code before the ‘</title>’ tag:

<?php if ( $paged < 2 ) {
} else {
echo (' | Page ');
echo ($paged);
} ?>

The full code used to generate my title is:

<?php wp_title(''); ?><?php if(wp_title('', false)) { echo ' |'; } ?> <?php bloginfo('name'); ?><?php if ( $paged < 2 ) { } else { echo (' | Page '); echo ($paged); } ?>

via Malcolm Coles