Wordpress - Change "Enter Title Here" help text on a custom post type

I know I'm a little late to the party here, but I'd like to add that the enter_title_here filter was added specifically for this purpose in WordPress v3.1.

add_filter( 'enter_title_here', 'custom_enter_title' );
function custom_enter_title( $input ) {
    if ( 'your_post_type' === get_post_type() ) {
        return __( 'Enter your name here', 'your_textdomain' );
    }

    return $input;
}

Change your_post_type and your_textdomain to match your own post type name and text domain.

There is no way to customize that string explicitly. But it is passed through translation function and so is easy to filter.

Try something like this (don't forget to change to your post type):

add_filter('gettext','custom_enter_title');

function custom_enter_title( $input ) {

    global $post_type;

    if( is_admin() && 'Enter title here' == $input && 'your_post_type' == $post_type )
        return 'Enter Last Name, Followed by First Name';

    return $input;
}

Sorry to dig this question up from grave, but there's a better solution provided since WordPress 3.1. The enter_title_here filter.

function change_default_title( $title ){
    $screen = get_current_screen();

    // For CPT 1
    if  ( 'custom_post_type_1' == $screen->post_type ) {
        $title = 'CPT1 New Title';

    // For CPT 2
    } elseif ( 'custom_post_type_2' == $screen->post_type ) {
        $title = 'CPT2 New Title';

    // For Yet Another CPT
    } elseif ( 'custom_post_type_3' == $screen->post_type ) {
        $title = 'CPT3 New Title';
    }
    // And, so on

    return $title;
}

add_filter( 'enter_title_here', 'change_default_title' );