Hello Android funs!
As we all know, many android phones, first being the HTC Dream (which I am glad to own, although I now use it just for testing apps), are featuring a LED on the front side of the device. This LED light comes in use when a notification is shown, which is usually accompanied by a sound, an icon on the notifications status bar, a ticker text on the status bar and a View that is shown, when the notification area is expanded!
As already mentioned, not all android phones come with a LED light, so if you are a potential buyer of a device based on the Android Platform, you should check the device specs first.
Also, it seems that the “poor” LED light is not there to decorate the already nice looking notification Views that can be attached to the Notifications sent by an application to the NotificationManager. So, the LED light blinks only when the notification is not viewable, when the device is on sleep and the screen is off.
This is when you should expect the LED light to flash, when a notification has come up (which uses the LED feature), but the device is on sleep.
This was something that took me some time to find out, and wanted to share with you!
There are so many threads on-line directing to nothing useful, which made me think that this could be another undocumented and unstable feature, which no one has explained clearly. But this is probably not the case.
So, the final statement is: The LED light on Android phones (if exists), will flash only when the device is in sleep mode!
Have fun with Android Platform!