U2 has no official meet and greet. I doubdt they will start on the next tour. They only have "guests". So you have to know someone basically to get backstage and unless you are close friends with the band you will probebly be put in the hospitality room and wont be allowed anywhere near their dressing room. Half the time the band doesnt even stop by this area, although I "hear" there is some good food sometimes!! LOL
They could do like Kiss and Van Halen are doing. They have a platinum package where you get to attend soundcheck and meet the band. VH charges $300, Kiss charges more. I kind of see it as cashing in though and almost hope U2 doesnt do it from that perspective. But being at soundcheck is cool, I'am sure alot of fans would pay to do it.