Seems our good old Apple just limited Lion Core reference to registered developers only.
So, even if you don't want to use the App Store, you may need to pay 99$ just to see the documentation. From posts I've made to other forums, I've seen tons of people that have the same problems. Is this a bug or a change in policy?
I somewhat feel robbed...
Here is one of the many links.
https://discussions.apple.com/message/15675613#15675613
P.S. I leave a small possibility that this is a bug in their servers. However, it doesn't seem like so, as many others have this problem.