very nice plugin, works perfectly on WP 3.4.
Although, I added a tiny upgrade - in akismet-htaccess-writer.php, after
"echo '<p>' . __( 'list of SPAM transmission former IP address', $this->ID ) . "</p>\n";" on line 369 I added this line:
"echo "<p> Blocked addresses: <b> ". count($this->iplist) . "</b></p>\n";". Now it shows me exactly how many IP addresses are blocked. It's fun to see how many spammers are banned ;)