Kris, as Dag says, trackbacks are the best way to get a lot of spam on your blog. I disabled the trackback module last year because I got flooded with spam. To test the current situation, I enabled trackback again Thursday evening. Result: 310 trackback spams in the moderation queue in less than two days!
I prefer to install a decent antispam and enable anonymous comments without moderation in that case. Since my antispam is active (Oct 2007), 18527 spams got blocked or more than 150 a day (yes, spammers seem to love me for some strange reason. *sigh*). If it would be able to filter trackbacks, I would reconsider to enable trackback, but right now it's absolutely out of the question.
Not sure if Drupal does
Not sure if Drupal does this, but it might be a good idea to allow trackbacks only from certain trusted blogs. If Drupal doesn't do this, then it can't be all that hard to implement.
i'm using wordpress +
i'm using wordpress + akismet on my blog, and don't have trackback-spam issues, akismet filters them all out nicely. i'm sure akismet can be integrated in drupal (for comments and trackbacks) as well?
There is an Akismet module
There is an Akismet module for Drupal: http://drupal.org/project/akismet . I don't have any experience with it, but I took a quick look at the settings and I don't think it supports trackback filtering. (I heard that the Drupal Trackback module doesn't have an API to interact with antispam modules.)
that's ... weird, no? i
that's ... weird, no? i mean, aren't trackbacks just a specific form of comment? i don't really know drupal, but shouldn't the trackback module be an extension of the comment module, enabling it to use e.g. akismet as well?
Trackback is a contributed
Trackback is a contributed module, so the exact implementation is chosen by the author. The trackbacks go into separate database tables and can't be seen as comments here...