Imagine if back in January of 1984, the release of the first Macintosh had been accompanied by over 150,000 applications—games, utilities, communications tools, you name it. The Mac would now be the pre-eminent personal computing platform on the planet.
Early in the morning of April 3rd, 2010, as the first eager Apple fans were picking up their iPads, the total number of available apps exceeded 150,000. Since most of these apps can run on the Apple's tablet, new iPad owners had immediate access to a huge library of creative and useful apps.
iPhone apps run on the iPad
The core of the first iteration of the iPad is iPhone OS 3.2, a version of the operating system that runs nearly every iPhone and iPod touch. OS 3.2 does include extensions that give developers access to features only available on the iPad. But Apple realized it would take some time for developers to become familiar with the new platform and release apps designed specifically for it.
Because of this, Apple designed the iPad to be able to run iPhone apps in an iPhone-sized window on the much larger iPad display. In addition, a 2X button situated on the iPad screen lets the user double the display size of an app to fill the iPad's screen. There's only one issue with that— app screens displayed at twice their normal size don't look as smooth or professional as those that are written specifically for the iPad.
Built-in apps take advantage of iPad features
The iPad comes with a handful of useful apps, most of which are familiar to iPhone and iPod touch users and all of which have been updated to take advantage of the iPad's larger screen. For example, Notes, which on the iPhone resembles a lined Post-it note, looks like a legal pad on the iPad, complete with a stitched black leather portfolio. Google's Maps app is now supersized, uses Skyhook's proprietary Wi-Fi geolocation service for pinpointing your location, and even takes advantage of the electronic compass built into the iPad.
Notes (left), Maps (right), and other apps have been updated to take advantage of iPad's features and screen size.
The Videos app plays movies and TV shows that have either been purchased through the iTunes Store or transferred to the iPad via the USB cable. The larger screen of the iPad is perfectly suited for personal viewing of video, and the wide viewing angle of the IPS (in-plane switching) display makes it easy to share that video with those sitting around you. 
For those of us who love cruising around YouTube, the YouTube app now plays your favorite viral videos in wide-screen splendor.
The iPad is well suited for personal viewing of video, TV, and YouTube clips.
The iTunes app benefits from the large screen treatment, making it much easier to search and purchase music and video from Apple's online media store. The iPod app is a gateway to all of your purchased audio media, and as with the iPhone, it plays your music in the background while other apps are in use.
Calendar and Contacts have the ability to sync to Macs, Windows PCs, and iPhones through MobileMe. In addition, both of these apps are much more useful in their larger format. In terms of looks and operation, the Day view in the Calendar app is the closest thing to a paper-based organizer I've ever seen on a mobile device. Contacts is much easier to read and search than ever before.
The Photos app is improved considerably over the iPhone version, with many features for organizing and displaying photos. Unlike iPhoto on the Mac, Photos has no editing capabilities so photographers who were hoping to give up their Macs will have to hold onto them for a bit longer (or wait for a third-party app to fill the gap).
The last of the built-in apps is Apple's Web browser, Safari. The app is no longer constrained by the iPhone's small screen, and the iPad version provides fast and fluid Web browsing. Safari's address bar includes an icon for quickly viewing all recent Web pages, a drop-down list of bookmarks, and (through Settings) a choice of either Google or Yahoo! as the search engine of choice. For those of you who were wondering, Safari doesn't provide Adobe Flash support.
Photos has many features for organizing and displaying (but not editing) photos. Safari (right) looks great on the big screen.
An unequalled eBook reader
Apple designed the iPad as a consummate media device by providing a free, downloadable eBook reader for the iPad. The optional iBooks app lets you read your favorite books and access Apple's new iBookstore. Although it's not as well-stocked as Amazon's Kindle store, its growing fast (see "iBooks" article, page 22).
I've used both stores and find that the quality of the eBooks available from iBookstore is better than those in the Kindle bookstore. They seem to have fewer errors in formatting, and the titles in the iBookstore often feature color covers and graphics that can't be duplicated on the Kindle or Barnes & Noble Nook. More importantly, the reading experience with iBooks is a joy. Turning a page is simple; simply flick your finger over the page like you would do with an actual book. The beautiful display of the iPad is backlit, so you can read your eBooks in the dark, and there is no annoying black "flash" when you turn a page like that on the Kindle's eInk display. As an eBook reader, the iPad is unequaled.
The optional and free iBooks app lets you download and read eBooks from Apple's new iBookstore.
iPhone OS 4.0 enhancements
No sooner had Apple introduced the iPad on April 3rd than they scheduled a press event for April 8th to talk about iPhone OS 4.0. This iteration of the iPhone OS won't be available on the iPad until sometime this Fall, but it promises to make the iPad even more useful. Some pundits criticized the iPad for not being able to multitask; that capability will be available in iPhone OS 4.0. Apple is also introducing iAd, a new mobile advertising service that will allow developers to place interactive advertising into their apps, providing them with a new revenue source. OS 4 will also include GameKit, a social gaming engine that will add a new dimension to game play on the iPad platform with OpenFeint-like score sharing and voice chat.
With the hundreds of thousands of apps available in the App Store, many iPad owners will want a better way to organize their app icons. OS 4.0 will also provide folders, each of which can contain 12 apps and have a unique name.
Mail on the iPad will become more Mac-like, with a unified inbox for all mail accounts. For those of us with many e-mail accounts, this alone will make the upgrade a necessity. For enterprises running Microsoft Exchange servers, iPhone OS 4.0 will provide the capability of having multiple Exchange accounts.
With the fall release of iPhone OS 4.0 for iPad, developers will be able to add even more incredible utility to Apple's latest tour de force. Based on the enhanced built-in apps, the number and quality of iPad-specific third-party apps already available, and the yet-to-be announced apps that will take advantage of OS 4.0 enhancements, we can safely say—the iPad has a long, successful life in front of it.
