Right this moment, if you visited the site, you will see a support message stating that the site is not accessible due to overwhelming demand.
Some Potter Heads who are also Tumblr users have blogged they've been on the site for hours and nothing is happening although these fans are not complaining but actually proclaiming their dedication to J.K Rowling's work. (Note the time difference, in the US it's only the 30th but already the 31st in other parts of the world.)
To all Potter Heads, GOOD LUCK!!!!