Can the almighty Google's second mobile payment plan challenge existing mobile payment programs? Probably.

That's not to say that Google is doing anything revolutionary or even all that different from what's already available on the market today. It recently applied for a new patent centered on SMS-based mobile payments. As Unstrung puts it:

A user would send an SMS to the GPay system to make a purchase in a shop, the amount of the purchase is debited from the user's bank account and credited to the shop's account, and an SMS is sent to the shopkeeper to confirm that the transaction has been processed.

This is almost exactly like PayPal's first mobile payment system, which also uses SMS to complete transactions. PayPal and Google aren't alone. Similar offerings are available from other firms.

So Google will offer to let users make everyday retail purchases with their phones. Nifty. This is also the aim of near-field communication (NFC)-based mobile payment systems. NFC systems use special radio chips that are embedded in cell phones and can be swiped at retail locations to make instant payments. NFC systems can be tied to bank accounts and credit cards. In the demonstrations I've seen, NFC is far faster than SMS when it comes to making mobile payments. Simply tap and go. No futzing with punching in codes and digital signatures. Right now, though, few phones in the U.S. are being sold with NFC capabilities built in and most phones are SMS capable.

What sets Google apart is that it has strong relationships with companies through its advertising business and can wrangle different fees. On top of that, Google also has its Mobile Checkout program.

But so far there's little evidence that the SMS-based programs are really getting off the ground. Can Google's entrance kick start things?