Announcing its first quarter fiscal results, U.S. iPhone carrier AT&T has revealed that it activated more than 1.6 million iPhone 3G units during the period. Of the 1.6 million iPhone 3G activations, over 40 percent were customers who were new to AT&T; the Q1 activation total compares with 1.9 million iPhone 3Gs activated by AT&T during the previous holiday shopping quarter—impressive given the typical post-holiday sales downtick—and…