Before the announcement of iPhone, building web apps for mobile devices was very hard to justify financially. We would never consider it because the market is too fractured with different devices with different standards. It was a complete nightmare.

Not anymore.
Better Mobile Browsing
The iPhone’s browser looks to be very close to Safari (this is just a guess, but a safe one I believe). This means that with some clever planning, web app companies like us can build apps that reliably work on both desktop and mobile platforms!
Access to standard OS features
Not only is the browser going to support standard web apps, but because the phone runs OSX, you’ll have all the standard access you’re used to when it comes to the OS.
Power to the people!
This blows open the market for web app companies. Now we can build web apps that can be used at your computer and on the go. Holy crap!
Of course, most web apps aren’t suitable (or useful) on mobile phones. However, there are a ton of great ideas that could be the perfect marriage of desktop (while you’re at the office) and mobile (while you’re out-and-about).
Not only this, but 3rd party software developers are going to have a hay-day with this. We should see an explosion of quality, useful mobile applications.
You may be saying, “Well, that’s great for everyone who owns an iPhone. But what about everyone else?” True, but if the success of the iPod is any indication, we’ll see massive worldwide adoption of the iPhone.
I can’t wait to think of our next web app idea :)

