DENVER - Barack Obama stepped triumphantly into history Wednesday night, the first black American to win a major party presidential nomination, as thousands of Democrats transformed their convention hall into a joyful, shouting celebration.

Competing chants of "Obama" and "Yes we can" surged up from the convention floor as the outcome of a carefully scripted roll call of the states was announced.

But even as he won the nomination, there was open talk in the convention city that Obama's race remained a stumbling block to winning the White House.

DAYTONA BEACH, Fla. - NASCAR placed Kyle Busch and Carl Edwards on probation Wednesday for the next six Sprint Cup Series races, the result of their on-track incident last weekend at the end of the race at Bristol Motor Speedway.

Edwards responded by driving the nose of his car into the right side of Busch's Toyota, spinning him out.

The postrace incident was apparently a reaction to Edwards nudging Busch aside with 30 laps to go Saturday night.