Either I have had terribly poor attention to detail, or the green light next to a person’s username (or lack thereof) indicating whether they are currently online is a new feature.
Tell me, which is it?
IIRC, it came with the last software upgrade.
You have had terribly poor attention to detail. It’s been around for quite a while. 
And as I recall, before that it was a check mark that would change color to indicate the member was online.
I was about to post a new thread, but I think I’ll hijack this one a bit, if I may.
How does the board know I’m not here anymore? When I open the boards, I’m automatically logged in. I understand that. But if I click away to a different site, I assume my little green light turns off. But how did the board know I clicked away?
What if I just close my browser window? How does the board know I did that? Is some sort of “logout” command being sent?
I would imagine it’s based on when you were last active on this message board website, i.e. when you last clicked somewhere here. It probably has a 10 or 15 minute timeframe after which it will change your status to offline if you haven’t clicked. Just a guess.