If anyone tries to login as the admin 3 times and fails they are IP banned permanently and I get an email of the IP address that tried it.
Within 2 days I started getting 2-4 emails a week per site and today I found this:
http://minus.com/lijJOdsVe8UD9
That's 149 IPs banned in a 24 hour period. My main blog got hit apparently by a cluster of hacker bots. If you run wordpress sites immediately install a login limiter or all-in-one security plugin like Better Wordpress Security:
http://wordpress.org/extend/plugins/better-wp-security/
You'll be amazed to see how many bots are trying to get into your cp.