Google quietly acquired mobile payments firm Zetawire yesterday, the deal having flown under the radar until analysts at the 451 Group saw a disclosure notice from the company's law firm, Fenwick and West, mentioning the acquisition.

So what's Google's interest in a low-profile, early stage startup like the Toronto-based Zetawire? Apparently, the Internet search giant wanted to get its hands on a particular patent the firm had been recently granted, one that hints at Google's larger ambitions in the mobile space: Google is developing a full-fledged mobile wallet technology for its Android-based phones.

The only notable asset the small Canadian company had in its possession at the time of acquistion was a patent application for "mobile banking, advertising, identity management, credit card and mobile coupon transaction processing." Yes, all of that, in one single patent. These are the ingredients for a complete mobile wallet application - one that can do everything, not just payments.

More Than Payments

That's a big difference from other mobile wallet initiatives we've seen lately, including the newly announced NFC (near-field communications)-based service called Isis, led by U.S. carriers including AT&T, Verizon and T-Mobile, as well as Visa's NFC-based In2Pay solution, which will be offered to customers banking with Visa's financial partners. Although both are major mobile payments initiatives, they both begin and end with the transactions themselves.

Assuming Google was after Zetawire's technology, it's clear that's Google's plans are a bit bigger. It looks like Google wants to do it all, from banking to credit cards to coupons flashed at checkout prior to the mobile payment itself.

NFC is Key to Google's Mobile Wallet

NFC is a technology that uses special chips to transmit data over short distances. All of the services in the Zetawire patent would presumably be handled by phones equipped with NFC chips, which Google's latest version of its Android mobile operating system (code-named Gingerbread) now supports.

Although at launch Android only allows phones to work as NFC readers, not transmitters, Google's mobile director, Jeff Miles, recently revealed that full NFC support was coming soon in a series of updates to Gingerbread itself.

Local Mobile Advertising Tie-In with Hotpot

Google's mobile wallet service could also be tied into the company's new Hotpot program, which involves a Yelp-like mobile application that lets you rate places (e.g. restaurants, bars, etc.) and then see recommendations that match your interests. Google recently began handing out NFC-enabled window decals to Portland businesses for testing purposes in a pilot program. To use the stickers, you simply point your NFC-enabled phone at the decal, and you're taken to the Google Places page for that location.

Put it all together and you get a complete solution for tracking the click-through rates (so to speak) of local, mobile, on-foot customers who tap a sticker, see a business's mobile Place page and then walk in to make a purchase, eat a meal, etc. And by handling the mobile payments on the backend, Google could presumably even track customer spending at these locations.

Local advertising (stickers, coupons, Place pages) + mobile payments (banking, credit cards, identity management)? Sounds like the holy grail for a complete mobile wallet technology. No wonder Google snatched up Zetawire.

Update: Corrected to indicate patent's status - has not been granted. See links in comments.