Because I've registered for this promotion on 6/10/2003 and still haven't received my coupon code, I have emailed Mastercard inquiring about this. Just received a response from them. Here's their response:
Thank you for your inquiry to MasterCard International.
Because the number of responses was far greater than expected there may
be
a delay in receiving the certificate.
Best regards,
MasterCard International
Customer Service Center
So, I guess we just need to be patient.