haha... you're familiar Alfie Kohn, aren't you?
I appreciate and validate effort over results... because I truly believe that most of us can be good at many things- but it is the effort and work involved that will take you there. I think that over or under praising kids can bring on praise hungry children who don't feel motivated from within, but through external validation.
It is all a dance, sometimes we're right on rhythm and sometimes we miss a beat. Generally I think that filling our children with our love and acceptance regardless of their accomplishments will send the message that they are valuable beings. What they achieve is really dependent on how hard they are willing to work for it... so i focus on that instead of how good or not so good something is.