It was just a couple weeks ago, that Square announced a deal with Starbucks, which will give customers mobile payment options in all of the coffee king’s 7,000 + U.S. locations. Now, PayPal  announced that it’s going to partner up with Discover to enable mobile all over the freaking place - 7,000,000 U.S. merchant locations. From AllThingsD:

Discover may not hold the same cache among consumers as Visa and MasterCard, but it reaches nearly as many merchants, roughly 95 percent of the two other payment networks combined. And when matched up with PayPal’s more than 50 million users in the U.S., the two could mark the first mobile payments network that spans both millions of users and millions of locations.

Mick (Visa) has the moves and Keith (MasterCard) has the licks, but the stones were nothing without Charlie Watts (Discover). You gotta have a back beat. Maybe Square can partner with Bill Wyman (Amex) and try to get back some satisfaction.
Expect to see the deal in action on the retail front next spring. The companies say that come April 2013, you will be able to use your PayPal card or phone number and a PIN (no card needed) anywhere Discover is taken.