Here is a quick screencast that shows how to instantly deploy Java web applications on the cloud with Heroku.
<iframe width="640" height="510" src="http://www.youtube.com/embed/PqLkjJvEMko?hd=1" frameborder="0" allowfullscreen></iframe>

If you want more than a quick introduction check out a [recording of my presentation at JavaZone][1]. And visit [heroku.com/java][2] for more details on how to get started running Java apps on Heroku.

 [1]: http://vimeo.com/28803302
 [2]: http://www.heroku.com/java