I think Chris is overthinking this. I didn't endorse anyone in '04, though I would've described myself as a "Dean sympathizer." In '04 the issues were Iraq and getting rid of Bush before he did all the things we imagined he'd do. So you had support for Dean and Clark (Iraq issue) and to a lesser extent Kerry (he's the most electable one).
Of all the reasons Chris lists for people not endorsing any presidential candidates, "divided community" is the only one that probably has any real legitimacy for me, and I felt the same way in '04.
But most importantly, who cares what I think? I certainly express opinions about the candidates, and those opinions might carry some weight with some readers, but I don't imagine that aggregating all of that into an "endorsement" of one candidate would really sway people. More than that, I don't see myself as the Voice Of Authority as editorial boards have forever.
If I woke up one day and really had a strong sense of which candidate I favored, I'd probably say so as more of a transparency issue, but I still wouldn't think of it as an endorsement.
Besides, I only go to dive bars to hang out with dirty fucking hippie bloggers. Otherwise it's only the finest restaurants for me!