If you have a Twitter account, more than likely, you have probably received or seen a message to this effect.
Every user was urged to change their Twitter passwords.
After you change your password, it’s also important to review the applications that have permissions to your Twitter account. e.g. if your Facebook posts automatically get posted to Twitter.
Some obvious apps to delete are de.licio.us and Posterous (remember them? exactly.) The rule is that if you don’t remember how or why you gave an application permission to access writing permissions to your Twitter account, its best to “revoke access.”
Personally, this is also a good time to review twitter accounts and see which ones are necessary and which accounts can be deleted