Fail2ban again
Yes, not long ago i shared my impressions from setting fail2ban up on servers in the company i work (link). And today i found this guide for preventing bruteforce attacks on sshd using Debian Etch & fail2ban.
P.S. In our company i also implemented vsftpd bruteforce attacks blocking with fail2ban. it took me to edit one line in a config file and redistribute this config to all servers using puppet 
two really great pieces of software.