It looks like Square has yet another competitor in the mobile payments arena. Global payment leader VeriFone has announced SAIL, a credit card reader much like Square’s, that will attach to a number of mobile devices. While VeriFone may have a little catching up to do, they have the advantage of an extensive network with a commanding percentage of retail transactions passing through their service.

Paypal has finally made it into the mobile payment market after being beat to the punch by the likes of Square and Intuit. PayPal may be late to the party but they have a more recognizable name in the world of payment systems and that may just be enough to push them to the front of the line. Besides their name, they’re also offering merchants a 2.7% flat rate on transactions versus the 2.75% offered by Square. PayPal didn’t stop there either, launching a full on geometrical attack by choosing a triangle as the shape of choice for their card reader dongle.

The heavily backed Isis mobile payment system is set to take on Google Wallet this summer and will be available to 100 Million U.S. cardholders. Chase, Capital One and Barclaycard have all signed on with Isis to enable their credit, debit and prepaid cards to be placed into the Isis Mobile Wallet. Isis is a joint venture created by AT&T, T-Mobile and Verizon Wireless and is the reason why Google Wallet was blocked on the Verizon Galaxy Nexus (which is anti-competitive IMO but we have a fix for that).