Twitter has been hacked again and had it's administrative panel (which shouldn't be web accessible) breached.
"This week, unauthorized access to Twitter was gained by an outside party. Our initial security reviews and investigations indicate that no account information was altered or removed in any way. However, we discovered that 10 individual accounts were viewed during this unauthorized access." - Twitter
Additional screenshots and information on the breach can be found at http://mashable.com/2009/04/30/twitter-admin-panel/
Twitter's Full Statement: http://blog.twitter.com/2009/04/unauthorized-access-update-on-security.html