I have dropped the ball on this one, but that doesn't mean you have to. There are several ABCT links up lately:
1. Gene on whether Keynes has a business cycle theory.
2. Jonathan discusses more of his view that the difference is really between the multiplier and the Ricardo effect. I need to read this one more closely in the near future.
3. Gene discusses how to get empirical on Keynes and Hayek. I agree with Gene that the sort of empirics he is describing here demonstrate the empirical adequacy of both theories. I am not sure if this is enough. One thing I always come back to is "what would these ABCT studies see if Keynes was right about the causes of recessions, but he also modeled a time structure of capital that was negligible as a determinant of recessions"? I think you'd see much of what the ABCT empirical literature shows. That's the problem. I don't really know of an ABCT empirical study that is able to arbitrate between them.
4. Read Steve Horwitz for what he says on ABCT, not for what he says on Keynes. I have only skimmed it so far, but if you want the Keynesian take, read Wren-Lewis on the same blog. I have plenty of discussions of the problems with Steve's jigsaw puzzle take on Keynes here. Brad DeLong posted a few things around that time agreeing with me, so don't think I'm some kind of lone ranger making things up to criticize Steve on.