Fantastic TED video of Paula Scher looking back at her career for those moments where she was able to devote time and effort to serious play and create wonderful work, and contrasting it with the unfortunate moments when the serious becomes solemn. I love how this retrospective observation of her career brings her to conclude that the best of times for her as a designer is when she comes into a project with no grounding or bearing--those times where lack of history or reference point allows that kind of play to emerge.
http://www.ted.com/index.php/talks/paula_scher_gets_serious.html