It's been three years since the GateGuruapp first launched as "Yelp for airports," a mobile app for navigating airport terminals with maps and user-generated ratings of services.
This afternoon, its iPhone version received its largest update yet. It amounts to a complete re-imagining of one of the world's most used travel apps.
GateGuru is now edging into territory occupied by trip itinerary service TripIt and same-day booking apps like HotelTonight.
GateGuru touts nearly 1 million downloads, 90 - 95% of which have been in the US. These updates could make it even more popular with users.
Here are the three biggest changes in the new iOS6 app:
Monetizes with rental car bookings. In an exclusive partnership with Avis Budget car rentals, users of GateGuru will be able to book advance and 11th-hour car reservations via dynamic pricing against available inventory and discounts off of retail rates. The deal is for US locations of Avis and Budget only. GateGuru gets a cut of any booking, of course.
Adds basic TripIt-like functionality. A user can now forward his or her flight conformation e-mail to plans@gateguruapp.com. All of the flight data, plus its airport content customized to your itinerary, will show up in the app. The app then provides relevant information at each stage of the trip, such as flight status, anticipated security wait time, rental car availability, and airport amenities.
Provides dynamic, instead of static, information. The app now updates its content to be relevant. Explains CEO and co-founder Dan Gellert,

"Once your flight departs, we are no longer giving you data around your departure airport.
So once your flight departs, we clear out the terminal information and the weather information from the top of the JourneyCard (the main overview of your journey).
What we don't do yet, but we may do in the future, is then auto-navigate to the next airport on the JourneyCard. Currently a user has to tap the arrow to do this."
Flash review
It's early hours, but we couldn't resist giving the app a test spin.
I signed up for a new GateGuru account (there are options for using an e-mail address, Facebook account, or Twitter account) and forwarded an upcoming trip itinerary email to GateGuru.
For my tastes, the GateGuru grey-on-black background was a bit too dark. I couldn't read the instructions and the company'se-mail address until I went into my iPhone's settings and pumped up the screen brightness settings. But perhaps that's just me.
I initially misread the e-mail address off the iPhone app and forwarded my confirmation itinerary to plans@gateguru.com instead of the correct address of plans@gateguruapp.com. D'oh! Not as straightforward as plans@tripit.com. But, again, user error.
Once I got the e-mail address right, the confirmation email went through, after a brief latency period.
On the app, my itinerary popped up. It was supplemented with offers for advance rental car deals at my destination, Philadelphia Airport. With a click, I was offered various types of cars for my dates of travel, with the option to adjust the dates.
There was no attempt to suggest what level of savings might be available, such as "X price is Y% off of the going rate," like is common on same-day booking apps for hotels. When I compared rates with Avis's own site for the same dates of travel and airport, the Avis website had lower rates. (That said, one example isn't representative, of course.)
If I had been a traveler needing to book at the truly last-minute and just wanted to do it on an app on the fly, GateGuru's tool could have been a useful service to have.
Overall verdict: A-. I'll definitely keep trying it on upcoming trips.