According to John Lange:
What tools are available to automatically firewall a given IP address if it fails to login via SSH a given number of times or any other activity which seems suspicious?
Google didn't seem to turn up much on this topic.
There's a thread of discussion here on that topic:
http://www.webservertalk.com/message962127.html
It mentions pam_abl, which I had happened across just last week, but haven't tried out yet. It's available here:
http://www.hexten.net/sw/pam_abl/index.mhtml
Sadly, I can't seem to find it as a prepackaged rpm for Fedora.