I have written a plugin for LifeType that blocks spam comments and trackbacks by blocking clients that are listed on Project Honey Pot's http:BL as having sent comment spam.
It is pretty cool that Project Honey Pot has made this API available to give access to the data that they have collected. In addition to the API, they have made an Apache module available to block http requests.
The download link will work as soon as the plugin is pushed to sourceforge. In the mean time, the plugin can be checked out of the subversion repository.