I started reading dKos daily in July '03.  He had the disclosure at the top of the page that he did some technical consulting for the Dean campaign.  About six months later he wrote a posting that mentioned that he actually hadn't consulted for Dean in a long time, but still had that up there just to offer full disclosure.

Meanwhile, he also wrote in a few postings about how he had been one of the original architects of the Draft Clark effort, then became frustrated that Clark didn't enter (he wrote this mid-summer '03).

I noticed that he sometimes wrote postings that praised something the Dean campaign was doing.  He also wrote some critical ones.  Same was true for many of the other Dem presidential candidates.  

It seemed like his disclosure suggested that he was supporting Dean, and that led a lot of Dean supporters to join dKos, but it was never clear to me that Kos himself was 100% for Dean.

In February when Kos formally endorsed John Edwards, I remember thinking that this was Kos' first formal endorsement of any presidential candidate.  

I think Kos did a great job of disclosing his consulting gig with the Dean campaign, creating a space where supporters of various candidates could feel comfortable, and pioneering all of this with no model to emulate.

Matt Stoller replied to Zephyr's piece on Zonkette with a comment about how any journalist or blogger will have some biases, whether they are paid or not.  It seems to me a regular reader of a blog will figure out those biases and read with that filter and skeptism.  When I'm not familiar with an author or a speaker, I always wonder about what their hidden biases might be.  Maybe everyone doesn't do that, but it seems like an important skill in the Information Era (or the too-much-information era).