It was painful watching Common Lisp happen; too many competing interests, and commercial stakes. Unfortunately languages went a different direction. (I also mourn Smalltalk's "loss", but Java had much more money coming into it.)
I really did not enjoy Lisp50. I was surprised to discover such a disconnect between the old-school and new-school Lispers. Guy Steele and co really didn't seem to have any interest at all in what people have done with Common Lisp these past 20 years or so. That is a pity because I had always really valued the perceived continuity of the Lisp community.
I read it differently; I think they thought it was an interesting direction, but only that, another direction. The oldbies are pretty CL-oriented, although obviously many of them have moved on (e.g., Fortress for GLS).
Lisp50 went into this somewhat (http://www.nhplace.com/kent/Papers/cl-untold-story.html) and, unrelated, was a freakin' awesome good time. I sat next to Guy Steele for one talk but was too in awe to even say anything.
(Anecdote about same: I IMed a friend and said "I'm sitting next to Guy Steele" and he replied "Cool, ask him who Guy Steele is." Damn kids.