Google is expanding its route map.

On Thursday, the company rolled out an updated version of its Flight Search tool, expanding the airfare-comparison service from the U.S. to more than 500 airports around the world.

"Since we launched Flight Search [last September], we've heard from many globetrotters eager to use the feature to search for destinations outside the U.S.," wrote product manager Eric Zimmerman in a blog post. "Starting today, you can find flights, including international destinations, from the U.S. quickly and conveniently."

That last part - that is, "from the U.S." - means you can search only for flights that originate in the U.S., but not those that originate elsewhere. It's also the latest indication of the company's iterative approach to new products.

"If you think of it from a release perspective, the original might have been version 4," said Ryan Williams, director of client services, travel for Compete.com. "This would be 4.1, not a jump to a 5."

As with the earlier version, users can access it in two ways. Using the Flight Search tool, users inputting their flight details see a map, multiple flight options and buttons that let you fine-tune the results by date, price and flight duration.

Using the company's main search box, you can simply enter, say, "flights Seattle to London," and the results will include several Google Flights listings, followed by links to FareCompare, Kayak, airline sites and others.

It's that latter aspect that has some in the industry worried as Google's search engine clearly gives priority to Flight Search.

"Anytime you search for a flight, they're instantly No. 1 and that pushes everyone else down," said Ben Hammer, spokesman for FairSearch.org, a consortium of online travel providers, including Kayak, Expedia and Travelocity, that was initially formed to fight Google's acquisition of ITA Software two years ago. (ITA runs the airfare-search technology for many FairSearch members.)

"More choice and more transparency is always good for users," Hammer told msnbc.com. "If users get to pick the winners and losers on the Internet, then they win. If Google picks the winners, Google always wins."

Not surprisingly, perhaps, the issue continues to evolve. Unlike the previous iteration, the new Flight Search includes links to an online travel agency (Orbitz) and Google has said it hopes to include others, provided the company's arrangements with the airlines allow it.

"If Google's really in the game to do its best for users, that's what they'll end up doing," said Hammer.

In other words, the expanded Flight Search isn't a game-changer, but rather, evidence that the game isn't over yet.