If you pay any attention to technology, you've probably heard by now that Apple Inc.- formerly Apple Computer Incorporated- has jumped head first into the mobile phone market with its introduction of the new iPhone.  The iPhone has all of the features of any smart phone including text messaging, a built in digital camera, the ability to surf the Internet, the ability to access email, and of course the ability to talk to other people like you would expect to be able to do on any device that's called phone.
In addition to all of the features that we can expect from a smart phone, Apple has thrown a variety of other features into this particular device.  In many ways, the iPhone isn't really a departure from the kinds of technology it's been developing, but rather adding smart phone features onto those other technologies.  The basic technology for the iPhone comes from the video iPod.  The iPhone has the ability to play digital music files as well as video and it can also view digital photos (but then you would expect that it could do that considering the fact that it does have a digital camera built in).
Apple has also chosen to take the iPhone in a different direction from its previous portable devices by including its OS X operating system on the phone.  The fact that one of the most advanced and secure operating systems ever created is running on a mobile phone is an impressive feat in and of itself.  In addition to the security provided by such an inclusion, the OS X operating system also supplies plenty of functionality that makes the iPhone a serious productivity tool in addition to an entertainment device.  Features like the Safari web browser, note taking applications, and other organizational features like a calendar and address book, make the iPhone productive as well as entertaining.
Of course, like many other portable devices, there are two barriers to making something as small as the iPhone easy to use.  First there's the small amount of space available for a screen and second there's the small space available for the keypad.  Apple has gotten around both of those issues though by doing away with a conventional keypad entirely while making the screen cover the entire face of the device and making it sensitive to touch.  That means that all inputs- be it dialing a phone number or typing a text message- take place through the screen.  It also means that when the screen is turned sideways it has a 16:9 aspect ratio just like movies and many of the television programs that are being produced these days.  In fact, the iPhone has directional sensors built into it that allow it to change the orientation of the contents of the screen when the unit is turned on its side.  That means that all you have to do to take advantage of the wide screen for watching video or browsing the Internet is turn the iPhone ninety degrees either direction and the image on the screen will accommodate.
Another hurtle that Apple had to overcome when developing the iPhone was the problem of having a touch screen on a device that routinely rides in pockets and is pressed against users' faces (when it's actually being used as a phone).  This design problem was overcome by the inclusion of special sensors which allow the iPhone to sense when it's close to an object larger than a finger (like a human face or the inside of a pocket) that wouldn't be used for input.   When it detects such a situation, the iPhone automatically turns off the touchscreen interface.  When it senses  empty space in front of the touchscreen, the iPhone automatically turns the interface back on.  In general, it seems that with the iPhone, Apple has though of everything.