Nick Milton's blog post earlier this week revisited the knowledge pyramid to suggest a variation (Revised Knowledge Pyramid (1) below) and I am going to suggest here a further variation (Revised KNowledge Pyramid (2)).. I don't think the original pyramid and this last version are meant to convey the same thing, so one is not better than the other. From my perspective, the original pyramid is a little too abstract and usually comes into the picture when trying to explain what knowledge management is, and in the context of inevitably trying to define knowledge (a lost cause in my opinion).
Therefore, when we talk about lessons learned, we should be talking about the entire pyramid, from the original experience to the action (what are you doing differently now based on what you've learned?).
I'm not completely satisfied with this pyramid though because experience doesn't seem to be the only way we learn. What we learn in school, what we learn from reading a book... those are not things we learn from experience, yet experience and prior knowledge are key in making sense of it all. When I access data and information, I can only make sense of it and transform it into usable knowledge if I have the required prior knowledge and/or experience. Experience-based information and externally-acquired data/information can both be the source of new knowledge.
When we train people, we are giving them new information and trying to present it in such a way that it will allow the trainees to make sense of it by connecting it to prior knowledge and experience. When training events start referring to "experiential learning", they are pointing to the fact that learning is more effective when the learners are experiencing a situation themselves and learning how to react to it.
Enough rambling for now!