Back at the turn of the century, when China began trying to crack down on the Internet, Bill Clinton said, “Good luck. That’s sort of like trying to nail Jell-O to the wall.”

He seems to have underestimated the ingenuity and commitment of Chinese censors, who in intervening years have put up the Great Firewall, some of the world’s most sophisticated machinery and software for controlling or blocking what reaches millions of Chinese Internet users. Many foreign services, including Twitter and Facebook, are blocked altogether, and the list grows by the week.

But the technical ability to nail Jell-O to the wall does not necessarily make it useful or desirable, as China demonstrated last Friday, when many users of Gmail in China found the service shut down.

Most of Google’s services have been disrupted since June, but until last week Gmail could still be accessed by its many Chinese users over protocols like SMTP or POP. These, too, went down. Chinese officials claimed to be flummoxed by the problem. But it looked for all the world like another attempt by China’s Internet nannies to either patch a hole in the Great Firewall or to intimidate Google, the biggest thorn in their sides.