I have turned off trackback support, since I started getting some trackback spams. I am going to see if I can extend pLog's Bayesian spam filter to process trackbacks. Also maybe it would be easy to write a plugin that will allow me to moderate trackbacks.
I still think that trackbacks are very useful, and I do want to support them.
Update: It looks like I will have to leave trackbacks disabled until pLog version 1.1. This would be a to risky of a change to do in the 1.0 tree. (Forum posting)