Auto block ALL IP's indicated by Akismet?

I'm thinking of blocking all IP adresses indicated by Akismet as containing spam. Something like cronning

select distinct wp_comments.comment_author_IP
FROM  `wp_commentmeta` JOIN `wp_comments`
WHERE wp_commentmeta.comment_id = wp_comments.comment_id
  AND wp_commentmeta.meta_value='true'
ORDER BY wp_comments.comment_author_IP

and then adding the IP's automatically to .htaccess.

Even better, I would like to post the current list of 524 IP's to a webservice to be sure hundreds of other people are also blocking the same IP.

Is that smart?

update now checking with http://www.dnsbl.info/ . Interesting e.g. 109.105.192.194 is listed with one of the spam database but not others. So I probably need to write a plugin that auto blocks the IP and then refer them to DSNBL if they want to unblock themselves. IS there already a DSNBL plugin?

update apparantly (ofcourse) there is : http://wordpress.org/support/topic/visitors-checked-by-dnsbl