This is really a useful plugin. I keep getting locked out email notifications at least 5 per week. Without this plugin we won't know if anyone trying to hack our wordpress blog. In the email we will know the username hacker tried to get into the system. And it is most often 'admin'. So better don't use admin as your username for wordpress blog. Choose something else as your username. If would be great if this plugin could send me the password hacker tried. That would help us in many ways.