Dave Snowden has a theory that innovation is triggered by starvation of resources, time pressure for a result, and a shift in perspective. See http://www.cognitive-edge.com/blogs/dave/2006/10/culture_and... where he makes the point

   Creativity is just one way, and not necessarily the most    
   effective to achieve perspective shift.  In fact I am increasingly 
   of the opinion that creativity is not a cause of innovation, 
   but a property of innovation processes, its something that 
   you can use as evidence of innovation, but not to create it. 

He has some interesting short videos up on http://www.youtube.com/user/CognitiveEdge that address innovation issues.