Twitter - block and unblock - can Twitter learn from Facebook
Someone got into my Twitter account. Not only did they get into my account, but they also deleted my followers. I am devastated. Not only does Twitter not have any mechanism for unblocking people your account has blocked unless you have an unbelievable memory for every person who has followed you, but these people who have taken the time to follow you and respond to your emails and links, think that you have blocked them.
So, change your password frequently and make sure it is not obvious. Keep track of who follows you (which is hard to do when you have thousands as we have) and lobby Twitter to provide a better solution to this problem.