So that's the monthly base rate, but what about the per-smartphone costs? Those are largely staying the same for new customers -- on-contract users pay $40 per line, while off-contract (Next and BYOD) customers get a discounted rate of $25 -- but AT&T tells us that existing on-contract customers will be able to take advantage of the discounted rate. This means that everyone who had been forking out $95 for an individual 2GB plan should now find themselves $30 richer each month, while folks with a $135 bill for two lines can whittle their monthly costs down by $45.
The catches? If you're on a contract and want to upgrade to a new phone later, the only way you can keep the discounted plan is to switch to Next or buy a phone at full retail.
The plan is also only offered to customers with one or two lines, so if you need any additional devices you're out of luck. While there are a couple restrictions, however, this is another in a string of aggressive moves by AT&T, which has been heavily involved in the pricing war currently underway in the US.
(Update: AT&T confirmed that the plan isn't restricted to just two lines -- just like the other Mobile Share Value plans, you can have up to ten devices for consumer accounts.)