Are My Ears Ringing?
TrackBack and Pingback are push technologies. Mark's Automatic linkbacks and my (unnamed) excerpting functions are pull technologies triggered by referers. The purpose of each is roughly the same: to bring my news to me instead of having me have to go foraging for it.
I actually experimented with mark's code for a bit, but the biggest problem I had was that it looked like it would require continual investment to weed out the ever growing number of portals and personal aggregators. I was also concerned about the feedback loop that could occur given the amount of back traffic I get whenever I mention anything on Mark's page.
By relying on links, I'm also weeding out people who don't have RSS feeds or can't follow instructions. Unfortunately, I'm also weeding out those who chose to remove the juicy bits (from a data mining perspective) from their weblogs. For my purposes, feeds like Mark's are best: they contain all the rich content yet provide a prepackaged, simple and clean excerpt for me to deal with. Or feeds like Burningbird's or Ben Hammersley's who chose to take the initiative and send the excerpts to me.
One thing that has pleased me is that I have noted that several people have added link information that wasn't previously there.