From an interesting article published on IndustryWeek: "Companies that consistently innovate are ones that invest in working conditions that enable workers to be creative. Simply ordering people to work harder and innovate probably isn't a great strategy."

Update: just realised the article is discussed in a post on one of the best blogs out there (IMHO): http://www.evolvingexcellence.com/blog/innovation_illusions/index.html

Among other things it discusses "where to find the time needed"