I have a lot to do with my day job (to the extent that I have one), and so all the thoughts I have on this post by Jonathan Catalan have not been written down yet. But it's an excellent post, and Jonathan has been doing a lot of thinking about this recently.
Briefly, the view of mine that he describes is that I think we can understand a lot of the differences between Keynes and Hayek by tracing each of them back to Wicksell. Then you see that the mechanisms they highlight are quite different, but not incompatible (and both trace back to Wicksell). There's no reason you can't have both - in fact Keynes toys with that in the GT. What is different is what they think happens with the actual rate of interest and the natural rate of interest in a depression. Keynes is more classically Wicksellian in a lot of ways (the interest rate is "too high"), but the important point is that this is where they really are different and can really be tested against each other.