Thanks for this.

I can dig allowing better identification, and highlighting user relationships.

Although I am against using pic avatars here for a number of reasons (policing them, aesthetic, distraction, etc.), I am more open to customization within some sort of constraints. insomniasexx pointed out that Designer News gives folk a pixel grid, which they can design however they wish. I also like Cedar's suggestion of choosing a color sequence.

I really like zebra2's suggestion of having information revealed as you reply to the user. It doesn't add much clutter, and it is a good time to remind the commentor that the parent was written by a human.

We were discussing this last night, and the idea of adding a note about a user came up again, much like rd95 suggested. Here's an example of something that might incorporate some of these ideas, it would be revealed when I reply to elizabeth:

In addition to interaction data, there are two tweet-sized notes. You can choose a signature that others replying to you see, and they can add a note on your profile page, which appears to them when they reply. There are a number of modifications we could make to this, including some sort of constrained avatar. Suggestions/alternatives?