Mardi Gras seems to go on forever, partly because it does. In New Orleans is lasts for several weeks and this year it was even crazier than usual because the New Orleans Saints won their first ever appearance in the Super Bowl right in the middle of this year's Mardi Gras season.
But the actual Mardi Gras DAY is TODAY. It varies each year because it is always the day before Ash Wednesday.
Check out these links for a little more info and flavor:
The New Orleans Site
Mardi Gras Parade Cam
Bourbon Street Cam (this one might not be active till the evening)