Help Green and Orange Dots on Some SMS Threads?

[SoonerLater]

I'm just getting used to my new Samsung Droid Charge. Mostly I like it better than the Droid-X that it replaced, but a few things are confusing or irritating. For example, I cannot for the life of me guess why some of my SMS threads/conversations are marked with a green dot, some with an orange dot and others with nothing. I'm sure that it's supposed to be obvious and maybe everyone else "gets it" immediately, but I'm lost.

 

[executor485]

The ones with green dots are the people in your gtalk/gmail contact list that are online/able to be IM'd with. The orange dots are people who are online, but they have been idle, or are away. The people with nothing are either not on your gtalk list, or they are offline.