Check out this Washington Post article (link requires registration):

(The Rev. Jesse) Jackson told worshipers at Ebenezer African Methodist Episcopal Church in Fort Washington that he launched the effort because Bush told members of the Congressional Black Caucus last month that he didn't know the landmark measure, signed by President Lyndon B. Johnson in 1965, is up for renewal in 2007.

[...]

Jackson plans to lead a march in Atlanta on Aug. 6, the 40th anniversary of the legislation's passage. He said a coalition of civil rights, labor and elected officials will soon release a lobbying strategy for the bill's renewal.
"We the people are not going back no matter who is in the White House," Jackson boomed. "We have come too far by faith and by fighting."

This is fear mongering, pure and simple. Jackson knows that Jim Crow isn't coming back. But he conjures and exploits fear purely for his own aggrandizement. Check out what the Urban Legends Reference Pages have to say about this nonsense:

The Voting Rights Act was never intended to be in force permanently. It was initially effective for a period of five years; that period was later extended for another five years, then another seven years, and finally for another twenty-five years, ending in 2007. Even if the Voting Rights Act is not extended again in 2007, this will not mean that the right to vote will "be taken away" from blacks — it will simply mean that the federal government will no longer require states to seek federal approval before changing their voting laws. We should see this as a positive — that we as a society have finally (if slowly and painfully) progressed to the point we no longer need to take special measures to ensure that every citizen has a fair opportunity to participate in a democratic voting process. There are times when we should get all riled up about what our government is doing, but this isn't one of them.

Dry up and go home, Jesse. We grow tired of your now quarter century old Chicken Little act.