Its definitely not down right now.
We restart it occasionally to install patches, but that is it.
I'm working on a post to update with this answer that will detail various ways that licensing may be blocked, but which are not actually the license server being down.
The short answer is that normally if your computer can't get licensed, its usually either a network/firewall issue or a permissions issue.
Stay tuned for an edit to this answer that will expound and clarify.
