Oh great. At the US Mint's website, they even have the three coins on the front page now, with "Pre-Issue Pricing Now In Effect!" and a "Now On Sale" link. Except that the link takes you to a page where they merely say you cannot order online.

If they only accept orders via phone or postal mail (not that great for US orders, and even more cumbersome for non-US customers ...), they should at least temporarily remove that ad from the Latest News window.
I have bought from them before, and usually it's pretty smooth and easy. And I am sure they had good reasons for switching service providers just in time for this pre-sale ... sigh.
Christian