Their website is overloaded by all the users trying to register new products. They don't have the bandwidth to support the amount of users they have today. Webkinz does this fairly frequently. It makes me very angry - don't sell the product if you can't support it with your technology. The online use of these products is a big selling point!
In a few days lots of the kids will lose interest in waiting for the website to do something and give up, never to return again. So, it will free up the bandwidth and you can try again. In the meantime, all those people who paid for access and got frustrated and never try again are the losers.