The friendly skies are about to get interesting.

It's been five months since regulators cleared Google's (Nasdaq: GOOG) $700 million purchase of ITA Software, but the world's largest search engine is finally putting the travel software to work.

Google rolled out at a search engine for commercial flights this week, scouring several carriers for the best rates.

After kicking the tires on a few routes this morning at I can't say that I'm terribly impressed. It doesn't seem as good or as intuitive as the comparative engines found at Kayak or even Microsoft's (Nasdaq: MSFT) Bing. However, that doesn't mean that traditional travel portals can rest easy.

If Expedia (Nasdaq: EXPE), Orbitz Worldwide (NYSE: OWW), and (Nasdaq: PCLN) dismiss the threat of Google Flights because of its limited scope and unfamiliar interface, they're missing the bigger picture. Big G remains the search engine of choice, and folks that may begin researching a possible trip through Google -- checking out area attractions, event calendars, and other common sense preludes to booking that just don't appear in traditional travel portals -- will be wooed by the convenience of a flight search within Google itself.

Don't judge Google Flights based on what it looks like right now or the dot-com giant's low-key rollout. Everything boils down to one simple question: At what point does it become more lucrative for Google to serve up direct flight information than to generate a paid click through a lead-seeking travel portal advertiser? It's not just about a single exchange. It's about seeing Google as the starting point of choice the next time that somebody is pondering a travel decision.

It's not just Google catching the flying bug. Baidu (Nasdaq: BIDU), China's largest search engine, snapped up a majority stake in ad-based travel aggregator Qunar earlier this summer. (Nasdaq: CTRP) has every right to be worried in China, just as the stateside portals should be concerned about Google Flights.

Yes, regulators were hesitant in approving the ITA purchase in the first place. The deal didn't go through until Google agreed that it would license ITA's technology to other companies through the next five years. It doesn't matter. If Google can find a way to make itself relevant in travel without diluting its brand for search in general, this lowly launch is going to gain some serious altitude.

You can reach for the airsickness bags now, travel portals.

If you want to follow the traditional travel portals, a dd, Orbitz Worldwide, Expedia, and International to My Watchlist.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.