If you took a look back over the past five years in the life of your company, in the midst of the successes, failures, trials--from outside or in, would you be able to say that your core values held up as is the case with Steve Jobs and Apple?
Were the values there to begin with? Have they been rendered helpless because they didn't serve as your "true North" when you needed something to help make sense of the chaos? One of the primary reasons to engage in the identification of the values of your organization is to be able to lean on them in the times when your company faces choppy waters.
If one of the most admired corporate leaders of our generation points to the core values of his company to guide him through some of the darkest hours in its history, you can rest assured that your own set of values will do the same for you. But like the values at work behind the scene at Apple your values must not shift over time. They must remain fixed in the midst of the turbulence of shifting cultural, generational and competitive pressures.