According to Tnooz.com, Apple has filed a patent for iTravel, an iPhone application that would allow users to search, book, and receive confirmations for flights, car rentals, buses, trains and hotels. With no official announcement yet, the most likely release date for this function would be this summer when the iPhone receives a major upgrade to its operating system.

What does this mean for the Kayaks and Travelocitys of the world? Not good news, especially when you think about how the iTravel functionality will be tied into your iTunes account, making billing and accessibility instantly a snap for millions of users. Plus, you know people will use it just for the chance to whip out their phones while boarding their flight in lieu of a handing over a boarding pass.

Jaunted.com’s taken up the Foursquare debate (noting the Frugal Traveler’s kind-of endorsement) on how useful this location-based social networking phone application is for travel. (In English, it’s a tool that tells people what restaurant/bar/attraction you’re at, and allows you to leave and read tips/reviews about that location).

But how useful is this kind of app for travelers? Would you really be able to plan much using it? How helpful are the tips/comments given its user-generated aspect? How many people outside a few major metropolitan locations are really using this thing?

I admit, I use it here in New York for probably no better reason than to kill a few seconds while I’m heading to the bathroom or waiting for a drink. Has it helped me find any great deals or discover any great new locations? Not yet, but perhaps down the road.

In its defense, what’s better during traveling than discovering a new restaurant or local hangout? I love trying to blend into the rhythms of a destination, and I like Foursquare’s ability to tell you what’s “trending” at that moment (where a lot of users are “checking in”), giving a newbie the inside as to the neighborhood’s hot locale. A great resource for those who love discovering local hot spots.

How likely am I to lug my iPhone around while traveling just to be able to pull up this app? Eh. I’ve found that the best ways to find the best places around is to ask real people. You know, people whom you can look in the eyes and carry out a conversation with. I guarantee they’ll have some great recommendations, tips, and insights, and I promise, they’ll have a very low likelihood of causing you to incur roaming fees.

Want to avoid racking up exorbitant fees while traveling with your iphone? Be prepared and check out this guide for prepping your phone for the trek through the wilderness of international telecommunications fees.

Probably the most obvious thing to do (with all phones) is temporarily add on a specific plan for the country you’re visiting ($5 brings your Mexico calls down by 40 cents). This also applies to data plans for your bandwidth-hoggging smart phone.

Your iPhone is also automatically roaming around the network checking for data and downloading e-mail. Make sure to turn both these features off while traveling or you’re going to be shelling out serious moolah for a bunch of facebook alert e-mails and twitter updates.

The best way to save money? Leave the phone at home, enjoy the sights, talk to people, and when you must, head to the internet cafe for that phone call home and to check your e-mail (or update your blog). Unplug yourself from the Matrix. It’s really quite a trip.

With over 50,000 apps already for the iPhone, figuring out which ones are the best for the intrepid traveler is the hard part. Lucky for you Travel + Leisure’s naming their top 11 travel apps, ranging from the basic — unit conversion, voice recorder — to the truly necessary — where’s the closest free toilet? And you were just using it to play solitaire. Pshaw.

UPDATE: I’ve been alerted by inside sources of another list of travel apps, this one coming from National Geographic, and it has 20, which is way more than 11. Which is better? You do the math. Here’s the list.