It's 100% confirmed that Sting is coming to New Orleans for Wrestlemania 30 weekend, however, that doesn't mean you should expect to see him in a WWE ring. While rumors have been rampant that Sting is WWE-bound, with "The Icon" himself stoking the fire by saying he only wants one more match, one against The Undertaker, he is not booked for any WWE appearances over the weekend.
Sting's appearance in New Orleans is for the independently booked WrestleCon convention and is limited to 250 people from 10:30 AM - 1:30 PM on Sunday, April 6, 2014. According to event organizers, his travel has been paid for and he'll be departing New Orleans after the appearance.
I've noted numerous times that Sting being booked for WrestleCon essentially eliminates him from the Wrestlemania 30 conversation. If he had a WWE contract and the company wanted his name in the public, they would surely promote him for Axxess. If they wanted to utilize him as a surprise, there's no way they would approve a third party booking the day of the show.
While it's unknown what this means for the long-term, Sting should be considered very doubtful to appear at any WWE-related events over Wrestlemania 30 weekend.