[meatgel]

Here's the info from the user guide:

9. Notification LED. This LED shows the following:
 Flashing green light when there are new text, picture, video, or email messages, missed calls, or reminders.
 Solid green light when the device is connected to the power adapter or a computer and the battery is fully charged.
 Solid amber light when the battery is being charged.
 Flashing amber light when the remaining battery level reaches below 10%.