Remove Gravatar on Admin Bar (Hintergründe: http://talkpress.de/artikel/wordpress-admin-bar-datenkrake-missbrauch)

remove_admin_bar_gravatar.php

<?php
/**
 * Plugin Name: Remove Gravatar on Admin Bar
 * Plugin URI:  http://talkpress.de/artikel/wordpress-admin-bar-datenkrake-missbrauch
 * Description: Remove Gravatar on Admin Bar
 * Version:	    1.0.0
 * Author:      Frank Bültge
 * Author URI:  http://bueltge.de
 * License:     GPLv3
 */

// This file is not called from WordPress. We don't like that.
! defined( 'ABSPATH' ) and exit;
// If the function exists this file is called as comments template.
// We don't do anything then.
if ( ! function_exists( 'fb_admin_bar_init' ) ) {
	
	add_action( 'init', 'fb_admin_bar_init' );
	function fb_admin_bar_init() {
		remove_action( 'admin_bar_menu', 'wp_admin_bar_my_account_menu', 0 );
		remove_action( 'admin_bar_menu', 'wp_admin_bar_my_account_item', 7 );
		
		add_action( 'admin_bar_menu', 'fb_admin_bar_my_account_menu', 0 );
		add_action( 'admin_bar_menu', 'fb_admin_bar_my_account_item', 7 );
	}
	
	function fb_admin_bar_my_account_menu( $wp_admin_bar ) {
		$user_id      = get_current_user_id();
		$current_user = wp_get_current_user();
		$profile_url  = get_edit_profile_url( $user_id );
	
		if ( ! $user_id )
			return;
	
		$wp_admin_bar->add_group( array(
			'parent' => 'my-account',
			'id'     => 'user-actions',
		) );
	
		$user_info = "<span class='display-name'>{$current_user->display_name}</span>";
	
		if ( $current_user->display_name !== $current_user->user_nicename )
			$user_info .= "<span class='username'>{$current_user->user_nicename}</span>";
	
		$wp_admin_bar->add_menu( array(
			'parent' => 'user-actions',
			'id'     => 'user-info',
			'title'  => $user_info,
			'href'   => $profile_url,
			'meta'   => array(
				'tabindex' => -1,
			),
		) );
		$wp_admin_bar->add_menu( array(
			'parent' => 'user-actions',
			'id'     => 'edit-profile',
			'title'  => __( 'Edit My Profile' ),
			'href' => $profile_url,
		) );
		$wp_admin_bar->add_menu( array(
			'parent' => 'user-actions',
			'id'     => 'logout',
			'title'  => __( 'Log Out' ),
			'href'   => wp_logout_url(),
		) );
	}
	
	function fb_admin_bar_my_account_item( $wp_admin_bar ) {
		$user_id      = get_current_user_id();
		$current_user = wp_get_current_user();
		$profile_url  = get_edit_profile_url( $user_id );
	
		if ( ! $user_id )
			return;
		
		$howdy  = sprintf( __('Howdy, %1$s'), $current_user->display_name );
	
		$wp_admin_bar->add_menu( array(
			'id'        => 'my-account',
			'parent'    => 'top-secondary',
			'title'     => $howdy,
			'href'      => $profile_url,
			'meta'      => array(
				'title'     => __('My Account'),
			),
		) );
	}

} // end if

Looks like not working in version 5.3.2.

What's the fb_ means?

That's only a prefix for clear namespace to remove problems with other functions.