Hi Paul,
Thanks for your preorder! The book is still scheduled to go to print on September. Please note that going to print is not the same as "will be delivered". From print to delivery could take up to 4~8 weeks. Like I said, though, we're still on schedule, which is good!
As for the email, I did set an automated email to go out once the buyer automatically returns to my web site after completing the purchase from Paypal. It may have ended up on your spam folder, perhaps? I'll check to make sure those emails are going out just in case. Regardless, rest assured your pre-order was accounted for.
Cheers,
Rogelio