While the iPhone has been a veritable gold rush for app developers it's debatable whether the opportunity still exists to make a killing with over 140,000 applications on Apple's AppStore, except of course for Apple.
So, does the iPad, which will run most iPhone apps unchanged present the next great opportunity for developers, particularly those who get in early?
Perhaps. Sure a number of developers will have overnight success like Australia's own Firemint.
But along with the emergence of decent Android-based phones (and soon tablets), Palm's webOS, RIMs Blackberry, Windows Mobile 7, and many increasingly sophisticated web-enabled phones, the arrival of the iPad underscores a particular challenge for developers familiar to those in the traditional mobile space: Platform fragmentation.
To develop native iPhone and iPad applications, you use the same programming language (Objective-C), but each has a significantly different form factor - iPhone 480px by 320px at 163dpi versus 1024 by 768 at the rather disappointing 132 dpi for the iPad.
You develop for the Android using Java, webOS using web technologies (HTML, CSS and JavaScript), and for various other smartphone platforms using a variety of these and other languages.
Not only that, but each platform has a different API for accessing device features like the camera, GPS location, compass and so on. This makes targeting a variety of platforms time consuming and expensive, indeed out of the question for most developers.
So, whether as a developer yourself, or someone looking to have an app developed, what's to be done? You could pick one, two, three or however many platforms you can afford or feel is strategically necessary to target. Adding iPad in addition to iPhone support won't be tremendously more expensive, but with Android seemingly gaining traction, can you afford to be left out there? What about the Blackberry? Palm's Pre? Where do you draw the line?
However, all these devices have something very important in common - each sports a desktop class web browser (most of them based on Webkit, the same core web engine that's in the iPhone and iPad).
By developing a web-based application (which in many cases can be installed as a "native" app, or can work even when the phone is offline), you can target most modern mobile devices with the same codebase.
With frameworks and tools like PhoneGap (and Titanium from Appcelerator, you can not only develop native apps for multiple mobile platforms with CSS, HTML and JavaScript, but even target the different device APIs (like a camera) with a single API.
So, while the iPad at first glance seems to usher in a new age of fragmentation even for iPhone app developers, it may just help developers see the light, realising that rewriting their apps from scratch, or substantially, for each new flavour of the month platform is unsustainable even for large development teams, let alone agile small groups.
Web technologies provide a way out of the traditional bind of platform specific applications. With no license fees, no vendor lock-in, a huge variety of tools and resources, and enormous communities of developers, web technologies are being embraced both by a new generation of developers, as well as more traditional desktop and mobile application developers. If you've not considered using the open web stack as the foundation for your appplication, now might be the time for reconsidering. HTML, it's not just for web pages anymore.
John Allsopp is a co-founder of the Web Directions conference series, and author of one of the earliest books on Microformats. As a software developer, long standing web development speaker, writer, evangelist and self proclaimed expert, he’s spent the last 15 years working with and developing for the web. As the head developer of the leading cross platform CSS development tool Style Master, and developer and publisher of renowned training courses and learning resources on CSS and standards based development, and author of the highly regarded “Dao of Web Design” he has been widely recognized as a leader in these fields. Visit the Web Directions website.