The "grand finale fireworks ending" of this Baez-o-gram is lovely: an abelian group object in the category SetsΔop of simplicial sets is just as good as a simplicial object in the category Ab of abelian groups. On the other hand, item H of the next one is stupefyingly beautiful: the result is another category equivalence, and it seems to be saying that both of the above things are just as good as a chain complex. I still haven't figured out why.
Man, I seriously didn't do much useful today. Went to the last lecture of Kleinberg's class, where he talked about some connections between VC-dimension and min-cut reductions. Went to the first part of the KGB meeting, but the election wasn't very exciting to watch since I wasn't participating. Ran into and had a chance to chat with dr4b at it, though, which was nice. Out of all my not-in-pittsburgh-anymore friends, there's something that sets apart pete, dee, and martin, and I'm not sure what it is. Some sort of pleasant constancy. Like, they could completely change in personality (and in fact pete has changed quite a bit in the, like, ten years I've known him) and still there's that bit of them left that was the reason you were friends with them in the first place that never really changes.