Same here; sent them an email and this is the response I got back:

Greetings,

Thank you for contacting O'Reilly Media Customer Service. Today we had a very heavy volume of orders due to our "ebook deal of the day" promotion. This is affecting the delivery and accessing of electronic media. We have verified that your ebooks are in your account. Please be patient and keep checking your account. We apologize for the inconvenience and appreciate your patience.

Best Regards, O'Reilly Media Customer Service