AT&T is offering a 50 percent discount on its selection of accessories for the first-generation iPad amidst reports of the next-generation model’s impending announcement. AT&T’s assortment of cases includes offerings from AGF, iFrogz, Incipio, Griffin, OtterBox, and Speck. As noted by Boy Genius Report, AT&T traditionally doesn’t offer such discounts unless a replacement is imminent; recent reports have suggested that…