The word "change" and the post office are not often linked, but that, in fact, is the assignment of the newly installed CFO of the U.S. Postal Service. H. Glen Walker must deliver change–and turning around the government-owned enterprise, charged with delivering 40% of the world's mail, will be no small task. But the Internet and other brand-name delivery services are eroding its first-class, high-margin business, and it must change or shrink.

The biggest challenge facing the soft-spoken Walker is reining in labor costs from a 676,000-person unionized workforce. Some spadework was done for him with the commitment of $5 billion over the past few years to automate processes. Now, he must realize the return on this investment by cutting an almost unimaginable 40 million work hours for a savings of $1.1 billion in 2007. But, admits Walker, "We are constrained by the types of agreements that we've negotiated in the past."

Before his current job, Walker was CFO at Invensys Controls, a $3.5 billion parts maker for heating, cooling and safety products. Coming from the private sector, says Walker, "I had all these ideas that this was a government job–that they had no idea what was going on in the modern world of business." He says he has been pleasantly surprised, but there's room for improvement.