A couple of debate-related links I found interesting heading toward tonight's VP debate:
"Six Things That Favor Joe Biden Over Paul Ryan in Tonight's Vice-Presidential Debate," by Avik Roy. I find this a plausible analysis, though on other hand Ryan is such an unknown quantity as a debater that pretty much anything can happen.
"Lessons from Obama's Debate Scare," by Jonathan Chait. Includes an unexpected note of cross-ideological comity.
UPDATE 5 PM: One more: "Obama's Debate Performance: How Twitter Has Done Us Wrong." This argues that Obama did poorly because he's a "long-form writer" in a time when journalists have become focused on the quick give-and-take. I'm skeptical. My experience of watching a lot of debates, and participating in some, is that in-depth writing is good preparation for debates--you have to have a lot of material to draw on, not just snappy comebacks.
UPDATE, POST-DEBATE: I think Biden had the edge, but a minor edge. He was obnoxious, laughed too much and seemed deflated by the end, but he was forceful and interesting. Ryan was middling for the most part, though occasionally pretty good and never outright bad. Overall effect on the race: probably very minor.