FORTUNE — Just two months after taking over Zuccotti Park in lower Manhattan, Occupy Wall Street has mushroomed into a national movement, with offshoots in cities from Miami to Seattle. With winter coming on and some local police departments moving to clear out the demonstrators, it isn’t clear where the protest goes from here. In one sense it doesn’t matter. Regardless of what happens to the 99ers and their encampments, American business leaders need to take seriously what the lessons are for them.

The anger that fueled Occupy Wall Street’s rapid growth isn’t going away. Polls show that up to half of Americans support the demonstrators or at least believe they reflect public opinion. In many ways the 99ers are drawing on the same popular sentiment that gave rise to the Tea Party: a perception that business and politics are rigged in favor of a privileged clique of insiders, particularly those connected to Wall Street. Extremists on the left and the right exaggerate that picture, but it rings true enough to provide the makings of a political swing against big business that could sweep up the two main parties. Instead of criticizing the Obama administration’s modest efforts to reform Wall Street and rein in excesses, the Jamie Dimons and Daniel Loebs of this world should be looking out of their limos at what is happening in America.

For years ordinary citizens looked on impassively as their incomes stagnated, their jobs were shipped to China, and a few lucky folks made out like medieval crusaders. Every year journalists (myself included) would point to the latest Census Bureau data showing that the top 1% of earners were taking a bigger and bigger share of the national pie. (Between 1979 and 2007, says a new Congressional Budget Office study, it went from less than 8% to 17%.) And nothing would happen. The U.S. seemed to be defying the historical truism that rising inequality eventually leads to social and political unrest. Not anymore. With the financial crisis, the bailouts, and the Great Recession, inequality has finally emerged as a potent issue. Increasingly members of the 1% are being asked where they got their sacks of gold.

Most Americans don’t begrudge great riches to anybody who works hard, takes real risks, and creates things of value. As evidenced by the positive outpouring for Steve Jobs, great entrepreneurs are still celebrated. But there is an implicit social contract that links rewards to effort and accomplishment. If many people now believe that corporate America has violated that contract, is it surprising? At many big corporations, the senior managers have seemed more interested in stuffing their pockets than building for the long term. Gargantuan pay packages are only the start of it. Think boards of directors packed with patsies, books cooked to juice earnings, potential whistleblowers silenced, golden parachutes, and finally taxpayers obliged to save expensively tanned hides. The thing that is really surprising is that it has taken this long for public anger to well up.

Lately some corporate leaders have shown they understand what is driving the outcry. Warren Buffett said he should pay higher taxes. Vikram Pandit, the CEO of Citicorp (C), offered in a Fortune interview to meet with the protesters, acknowledging a lack of trust in Wall Street. Citi and other big banks wisely chose not to follow the lead of Bank of America (BAC) in imposing fees for using debit cards. But too many people in finance are acting as if it were 2007. Whether it is investment bankers griping about Obama being a closet socialist, Wharton MBA students chanting “Get a job” to OWS protestors, or the Chamber of Commerce, once a moderate voice, using its money and clout to try to preserve George W. Bush’s tax cuts for the rich, the message conveyed is the same: We don’t get it!

For an economic elite whose perquisites ultimately depend on the acquiescence of everybody else, it is a silly and dangerous pose to strike. If only for its own sake, the 1% needs to show a bit of nous.

–John Cassidy is a Fortune contributor and a New Yorker staff writer.

This article is from the November 7, 2011 issue of Fortune.