During his swearing-in ceremony in November, Mayor Kevin Johnson vowed to raise the city's profile. "My job is to be Sacramento's biggest cheerleader," he said, "and to spark interest in our city nationwide."

Since then, the mayor has learned that showcasing the city has its risks and rewards.

Sacramento shined during the prologue of the Amgen Tour of California. But then some thief stole Lance Armstrong's bicycle.

Sacramento was then featured on "The Oprah Winfrey Show," but the focus hardly inspired any civic pride. Lisa Ling, a friend of the mayor's, shined a harsh but needed spotlight on her hometown's growing homeless population.

On the plus side, the Oprah publicity proved beneficial for some of the city's homeless charities.

Scores of people around the country sent donations to Loaves & Fishes and the St. John's shelter for women and children, two groups highlighted in Ling's report.

That brings us to the city's latest encounters with celebrities – the mayor's use of them to highlight his broad and ambitious agenda.

Civil rights leader Jesse Jackson came to town this week to help Johnson kick off Volunteer Sacramento, a yearlong campaign to recruit residents to give back to the community.

This is a fine idea. With the economy in tatters and schools and social services facing cuts, volunteers can provide essential services as teachers, mentors and helpers at food banks and other charities. Sacramento residents stepped up to help after Hurricane Katrina. That same volunteer spirit needs to be tapped again.

The mayor has invited several other public figures to Sacramento on Monday for a summit on local public education. These include Joel Klein, New York City's education chancellor; Michelle Rhee, chancellor of the Washington, D.C., schools; Newark Mayor Cory Booker; and a controversial figure who has co-founded the Education Equity Project, the Rev. Al Sharpton.

Whether or not you support Johnson's brand of school reform, it should be worthwhile to hear what lessons Klein and other education leaders can offer to Sacramento. While the mayor has no direct authority over the city's schools, he can use his platform to spark debate and focus priorities. That appears to be his aim with his education summit.

Around the world, there are numerous examples of celebrities using their fame for the public good. U2's Bono has become the face of debt-relief efforts in Africa. The late Paul Newman, with his food products, raised hundreds of millions of dollars for charity.

Yet you can also find celebrities who jumped on causes, only to drop from sight when they became overextended.

The challenge for Johnson, a celebrity himself, will be to avoid this trap. This week, his message was volunteerism; next week, it will be education reform. He also has ambitious plans for gang intervention, a tent city for the homeless, high-speed rail, green-tech businesses, the waterfront, and the list goes on.

While the mayor may be able to make simultaneous progress on all these fronts, he risks spreading his star power too widely. At the end of the day, he'll need to demonstrate that substance has come from these celebrity summits. That isn't sexy. It involves the mayor's least favorite word – process. But it's a reality of being the mayor and not just another celebrity.