Any time I learn about a new tech or shiny thing, I search for it on HN and read as much of the back and forth as I can. A number of times I've noticed those conversations didn't happen that long ago, even on old threads. Having it there is pretty invaluable to me to get perspective on stuff.
I actually think that coming up with a way of tying those old posts back into the new posts to continue growing those conversations would be nice. (take that as a total aside; I'm really shooting from the hip by even saying that, because any implementation I'd say would be an idea I had uh, well about ten seconds ago, when I suggested it, and it's not really relevant to the point at hand)