WordPress 3.1 is about to release and one of the biggest changes is the Admin bar. WordPress.com already has a admin bar. If you would like to disable it, you can use a plugin, or add some code to the functions.php. If you would like to disalbe the Admin bar for yourself. Go to Users -> Your Profile. There you can click on the checkbox if you would like to disable the Admin bar in the dashboard and on your website.
Joost de Valk wrote some more about how to disable the WordPress Admin bar by add some code to the functions.php of your theme.
Of course there are already a lot of plugins that can also disable the Admin bar. I really like the plugin called: Admin Bar Minimiser. It doesn’t disable the Admin bar. It just adds a little option to minimise the Admin bar. It’s a simple solution, and I like it.
To check out the WordPress Admin bar, you must run the latest beta version. It not recommend to do if you are not an advanced WordPress user.