If you're a little confused about how or if your life will change thanks to the Justice Department's payment card announcement on Monday, you're not alone. So let's review what we know and engage in some mild speculation.

The government simultaneously filed suit against -- and revealed a settlement with -- Visa and MasterCard. As a result, merchants are now free to offer consumers incentives to use certain Visas or MasterCards that cost the merchants less to accept than other Visas and MasterCards.

Often, rewards cards, like the Visa credit cards that come with the word "Signature" on the front, cost merchants more than debit cards or plain vanilla Visa credit cards that have none of the rewards or premium services that might come with a Signature or other similar card.

Meanwhile, American Express is also a target of the suit, but it refused to settle. Why? Because its merchant fees are even higher than those of Visa and MasterCard, and stores would like to find a way to encourage people not to use American Express cards. (Sure, stores could stop accepting American Express cards altogether, but that isn't practical for most larger retailers since so many people have them.)

American Express's biggest nightmare is waking up one day to a world where any store can post a sign announcing a 4 percent surcharge for use of its cards while surcharges for Visas and MasterCards are 1 to 3 percent. So American Express battles any attempt to disrupt the status quo, even if it wouldn't lead immediately to surcharges.