How are they changing the Web? The obvious is iPhone apps are increasingly allowing people to access online content during times when they didn't have access to it before, therefore the increasing availability of mobile web access in general is continuing to speed up information sharing. What's interesting is some of the more impressive apps are not just displaying their content in a mobile-friendly manner, but also coming up with unique ways to engage their users using interactive features and digital media. More specifically, social networking apps like the ones for Twitter and Facebook are allowing people who are connected on the web to continue their relationships away from their computers. The rising popularity of iPhone apps with location-based capabilities (and soon to come the iPhone version of Google Latitude) are creating useful ways for people to access relevant data about events, businesses, and even people that are nearby.

How are they being used by brands? The smart brands are the ones that have already thought of ways to connect with a large base of all iPhone users (Kraft, Obama, Audi, to name a few). Most other major brands are most likely in the process or just starting to think about developing an iPhone app because of the successes they are continuing to hear about. But only a select few out of the rapidly growing database of 20,000+ apps with be successful because they will either be really useful, linked to a well-liked brand, or very creative. The longer it takes for the app to be released, the smaller the chance of it being successful. It's worthwhile to note that companies like Remember the Milk, Salesforce, Mint.com are creating iPhone apps to supplement their web services as an added benefit to offer to their customers. Shazam is a great example of a service that was not popular until it was available on the iPhone and started seeing tons of new users.

What about publishers? They need to recognize that besides an electronic reading device like the Kindle, people are already browsing their content from the iPhone (and most likely not having the best experience). Why not have a dedicated app that presents that content in an easier-to-read format? Even though it will take time, the iPhone will be a big advertising platform for publishers in the future. Besides newspapers, I think most major magazines will have iPhone apps soon. What they will need to figure out is what type of revenue model they choose because as of now the app store does not allow them the freedom of charging readers a monthly fee to download the latest content. The first successful magazine app will owe a lot of it's success from free PR and it looks like Lucky Magazine and People Magazine are very close to launching iPhone apps.

How are they affecting the gaming industry? The cost of the app plays a huge factor, but not as much as you might think. When it comes to gaming apps on the iPhone, people are willing to spend $5-$10 on good game because it's an inexpensive alternative when compared to most video games that cost over $40. It's only a matter of time before more live games on the iPhone that are constantly connected to the web gain in popularity just as we saw happen for all the major gaming consoles over the past couple of years. While no one is sure yet if increasing sales of iPhone games are damaging the sales of the major players, it doesn't take a genius to realize they are very likely to already be hurting the sales of other handheld gaming devices.

Some further reading: 8 reasons for building an iPhone Web application, Mobile ROI: You get what you pay for, and iPhone now represents 51% of U.S. smartphone traffic.