I emailed Bill Ray (the article author) about this being incorrect and that it was the time zone thing posted many times before so I won't repeat.
Anyway a corrected version is now on its way through editorial and so it is still on for today!
No direct quote from Apple which is annoying. We'll know if they've tweaked the OS presumably by the different version numbers. Not that the UK would have had it early today anyhow.
Edit - so it was just the author not realising the time difference might mean if it's released late on US time, if it's simultaneous release in the UK, it'd be released tomorrow?