I don't think there's any question that the creative class jobs that drive our innovation economy — designers, engineers, scientists, architects, entrepreneurs, writers, etc. — are all positions that require constant learning and evolution. In a larger sense, our economy, the companies that survive and thrive, the types of jobs in demand, and the skill sets required to successfully compete for these positions, are changing at a rate faster than we ever could imagine.
The Fast Company article, "This Is Generation Flux: Meet The Pioneers of the New (and Chaotic) Frontier of Business", has an interesting take on this phenomenon, framing the current economic environment as a system caught in the throes of creative destruction, brought on by rapid technological innovation and radical business model changes. A related article, "The Four Year Career", examines the imminent demise of the long duration job and the well defined career path.