Forty-seven airports, including Las Vegas, San Jose, Boston, Baltimore, Burbank, Houston, Indianapolis, Seattle, Miami, Ft. Lauderdale, Orlando, St. Louis, and Charlotte, are part of the holiday cheer. And once the project is over, the Burbank and Seattle airports will offer free Wi-Fi indefinitely.

"We're very happy to extend our Holiday Wi-Fi gift to the millions of people who will spend time in airports over the next few months," said Marissa Mayer, vice president of search products and user experience at Google. "We know that this is a very hectic travel season for people, and we hope that free Wi-Fi will make both traveling and connecting with friends and family a little bit easier."

The Convenience of Wi-Fi

The Thanksgiving, Christmas and New Year's holidays create one of the heaviest travel seasons of the year. According to FAA estimates, more than 100 million people will pass through the 47 participating airports between now and Jan. 15.

Due to bad weather and other extenuating circumstances, travelers often have extra time in the airport after they pass through security. Wi-Fi is handy for road warriors, bored children, and others who just want to surf the Internet.

What's more, a recent study by the Wi-Fi Alliance reported that 50 percent of business travelers take red-eye flights in order to be "reachable" during business hours, and an overwhelming 82 percent said being connected through Wi-Fi would help solve that problem.

"In addition to the obvious bonus holiday travelers will enjoy, sponsored access will increase overall Wi-Fi usage in the participating airports and help supplement the airport's increasingly important non-airline incremental revenue," said Dave Hagan, president and CEO of Boingo Wireless.

What's in it for Google?

Once travelers log on to networks in any of the participating airports, they have the option to make a donation to Engineers Without Borders, the One Economy Corporation, or the Climate Savers Computing Initiative. Google will match the donations made across all the networks up to $250,000, and the airport network that generates the highest amount per passenger by Jan. 1 will receive $15,000 to donate to a local nonprofit.

But what's in it for Google? It's all about advertising and branding, according to Greg Sterling, principal analyst at Sterling Market Intelligence.

"This doesn't really get Google any new awareness or usage, although it may incrementally generate additional searches from people who wouldn't sign on otherwise. Some of those searches will generate clicks and revenue. I'm not certain how much this costs Google, but some percentage of the fees will be covered by the new clicks," Sterling said. "Google's also got a charitable-giving promotion with this. So overall, it's mostly a feel-good promotion for Google. Bing is doing something similar."