Yes, I also have seen it on a few rare occasions, but I have no idea what it signifies.

 

There is/was a recent thread on that, plus the trackball: http://androidforums.com/htc-droid-eris/26253-trackball-notifications.html


.

 

I am not referring to the trackball. I am speaking of the "charging light".

 

I believe it means you have a Google email

 

The above trackball post talks about the charging light and the trackball. To summarize:
Green light for Gmail.
Trackball for Mail (HTC version), Messages, Google Talk notifications.

 

You can adjust it in your notifications settings. You can change the color of the light if you want too.

 

Like to know how you can do this ? --- I can only find the option in (display) to chose which items to check for a notification. The only option is for the "trackball" to light up. No options to use "LED" for notifications

What gives ?

 

The only time I've seen an option for changing the color of the LED is in Handcent, it has options for red, blue, etc, though people on this forum have said that it doesn't work that way on the Eris, since the Eris only has green and orange.

Some have said that the Moto Droid supports multi-colored LED, but I don't know that for sure.