SSL Certificate assistant repeatedly fails with "We are not able to generate your Profile at this time."

The Apple Push Notification service SSL Certificate Assistant in the developer.apple.com Provisioning Portal isn't generating a certificate.

I'm following the instructions:

1. I created a fresh Certificate Signing Request using the email address associated with my developer id in the "User Email Address" field, and my name in the "Common Name" field, and saved it to disk.

2. After clicking continue, I select the CSR I just generated, and click "Generate".

3. The assistant displays "Your APNs SSL Certificate is being generated... This can take up to one minute" for a little over a minute, then...

4. I receive an error dialog that says

We are not able to generate your Profile at this time.

Please try again later or try using the Provisioning Portal."

(note: I am using the Provisioning Portal)

Is anyone else experiencing this problem - or might I be doing something wrong?