Let the carrier wars continue. AT&T has just announced that it is dropping the price of its two-gigabyte Mobile Share Value plan by $15 in total. AT&T’s 2GB plan currently costs $55 as a base price. That’s dropping down $15 to $40, which represents most of the savings one’s going to typically get as part of AT&T’s new changes. From there, a potential plan purchaser has to add in the cost of one’s smartphone to the mobile plan: $25 for non-contract phones and $40 for those on a two-year smartphone service agreement.