The $page isn’t an array, it is an object. In this sense, using print_r (print array) probably isn’t the best option. Consider using var_dump as an alternative OR you can actually access the object properties directly like this:

$post->ID

This also allows you to set this as a variable for use outside the loop, e.g.

$curr_post_id = $post->ID

I am using this to imporve the WordPress pagination function on a site.

$content .= print_r($post, true);

get_the_ID() is handy for templates aswell in conjunction with the get_page and get_post functions.

Sean