It's the RTM date; the code is "off to the presses". In this day and age of continuous updates and Go Live licenses, RTM doesn't mean much anymore for the end-user. So, yes, I guess you could say that it's confusing, but it's a big milestone for the teams involved.
It doesn't look like individual developers can sign up yet, I am getting this error "You need to register as a company account, or have a registration code, to continue. Learn more"
EDIT: And I mean the title of the blog post itself. I understand that the link here is just echoing the post's title.