Why Can't I Sign In to Xbox LIVE?

Xbox LIVE is down
I Can't Sign In to Xbox LIVE! As of this morning people have been having difficulties signing in, instead being greeted with "Can't connect to Xbox LIVE. Select Test Connection to troubleshoot, or try downloading your profile again." of course doing either of those two things will do nothing because as of right now there is no explanation to just what the heck is going on here. Checking Microsofts official Xbox LIVE service page will give you brief update that's really nothing:

We are aware that members are still having an issue signing into Xbox LIVE. We greatly appreciate your patience during this time. We will continue to keep you informed on our progress as we work as quickly as possible to to get things back up and running. Keep checking back here every 30 minutes for an update.
Xbox Live Service

So yeah, pretty much Xbox LIVE is down.

When is Xbox Live going back up?
You can check back every 30 minutes or just accept it that today there will be no online play... --and you're paying for it. The longer this takes to fix the more free stuff you can expect to get! At least that's what happened in the case of Sony's PlayStation Network going down back in 2011

Official Xbox Live Status Page
Xbox LIVE Service Status