I've previously written about Kim - particularly her conversations and articles at uie.com - and I love her attitude and approach to this user experience technique. Kim says:
Combining storytelling with research data can help you craft realistic scenarios to guide your design process.
Developing Effective Scenarios - uie.com podcast with Kim Goodwin (35 minutes, transcript available)
My previous post about Kim Goodwin, personas and scenarios (August 2011)