One aspect of the Apple iPhone that I can't stand is the lack of quickly viewable notifications and I am actually very surprised that Apple doesn't have a better system in place on the device. Then again, I think the notification system for most mobile operating systems can be improved. On the iPhone, the notifications appear for a few seconds and then disappear. You then see a notification indicator on the text messages, email, and phone icons, but you have to go into each application and sometimes you may not even have that application on the visible "home screen". According to MacRumors Apple has filed a patent application for a cool new notification screen. It is a bit strange that a patent would be needed for something like this that even basic feature phones already use in some manner.
This new notification screen would show your missed calls, text messages, and voicemail on a single display before you slid to unlock the iPhone. Other notifications may be supported on this display as well and this looks like a nice implementation.
On Windows Mobile, notification pop-ups appear after turning on the display, but most devices do have indicator lights that flash to let you know there are notifications. On most new Windows Mobile devices the left soft key changes to "notification" so you can quickly go through your notifications once you turn on the display. On some devices, the notifications show you part of a text message and other information so that you don't even have to go into the application to view the notification. You can even respond and take action right from the notification. With the open nature of the Windows Mobile OS you can also tweak notifications to your liking with registry hacks.
Palm seems to do a better job with notifications and I really like the glanceable status display on the new Treo Pro that shows the time, date, and basic notification status when the colored display is off. The Palm OS also has useful notifications.
S60 notifications are also quite useful and the implementation on the Nokia E71 is fantastic with their Standby screen bottom notifications that I will explain in full detail in my review next week.
On my BlackBerry Curve the indicator light flashes if the display is off and when I turn the display on notifications show up as icons in the top status bar. These vary by the type of theme you have selected on your device.
You can customize these other mobile devices to setup a Home/Today screen to show all of your notifications and other glanceable information (appointments or tasks for the day) and maybe Apple should think about having this kind of functionality on the iPhone.