Chain letter and hoax, though originally based on reality. Here's Spaf's Craig Shergold FAQ. The disclaimer at the bottom indicates that it can (and should be) reposted.
DO NOT SEND ANY {GET WELL, POST, BUSINESS} CARDS TO CRAIG SHERGOLD!

If you contact the ``Children's Make a Wish'' foundation, you will find that they are not soliciting any form of card for Craig Shergold or anyone else. Better yet, if you call the publisher of the Guinness Book of World Records (US publisher is "Facts on File" @ 212-683--2244 ext. 336), you can get this same story confirmed. You will also find that they will no longer endorse or support any effort to break this record.

Many years ago, Craig Shergold developed a brain tumor, believed inoperable. He sought to set the Guinness record for get-well cards. The effort was well-publicized around the world, and he did, indeed set the record (consult a recent edition of the book (p. 207 of the 1992 US edition, for instance) --- he has received in excess of 33 million cards to date; he officially set the record as of 17 Nov 1989).

As part of this whole story, his plight caught the attention of John Kluge, the US billionaire, who paid for Craig to come to the US and receive specialized treatment. As a result, Craig has recovered completely from his non-malignant tumor. He is also no longer seven, but twelve (as of January 1992).

The problem is that the mimeographed sheets and letters seeking cards for Craig have continued to be circulated. As a result, get-well cards continue to pour in to the post office for Royal Marsden Hospital in England. Worse, the appeal has mutated into various other versions, such as an appeal for business cards, one for postcards, and another version that appeals for holiday cards.

The Shergold family has publicly appealed many times for people to cease to mail cards and letters, and that no more appeals be made on their behalf. One easily accessible way to verify this is with the article on page 24 of the 19 July 1990 NY Times. People Magazine wrote an article about it on June 1, 1991, page 63. Many other publications have also carried stories on this; even Ann Landers wrote about it on 6/23/91, but people still keep sending cards. Both Guinness and Royal Marsden have repeatedly issued press releases asking people to stop circulating requests for cards, as they are creating an undue burden on both the hospital and the postal service.

The Guinness people have discontinued the category to prevent this kind of thing from ever happening again, and are doing their utmost to kill any further mailings. The Royal Marsden Hospital is at a loss what to do with the cards that continue to arrive --- most are being sold to stamp collectors and paper recyclers, and none go on to Craig.

This appeal for Craig, as well as many urban legends, regularly appear on electronic bulletin boards around the world, and in many organizational newsletters and bulletins. It is both heartening and unfortunate that there are so many well-meaning people who continue to propagate these stories. It is too bad that so many of these people are unwilling to verify their information before passing such things along, especially when a simple phone call will suffice to do so. In this case, opening a recent copy of a book carried by nearly every library and bookstore would illuminate the situation.

If you would still like to do something for a dying child, consider making a donation to a charity such as UNICEF or to the International Red Cross (Red Crescent, Red Magen David). Many thousands of children are dying daily around the world from disease and starvation, and countless millions more are suffering from the ravages of war, famine, disease, and natural disaster. Think how many of them might be helped by the millions of dollars in postage spent on cards to Craig Shergold.... Addresses (in US) are:

        UNICEF               American National Red Cross    
        1 UN Plaza           17th & D Streets               
        New York, NY 10017   Washington, DC 20006
        Attn: international children's aid
Also, I encourage you to save this announcement, in either electronic or hard copy form, and to post it anywhere you've seen the original plea. If you see it in the future, as you probably will, you can attach a copy of this announcement.
--
Professor Gene Spafford
Dept. of Computer Sciences
Purdue University
W. Lafayette IN 47907-1398
Spaf@cs.purdue.edu

kd adds: Watch out for mutants of this hoax. Typically they give an email address and say "every email sent to this address will donate a penny to a child in need" or some similar junk. Don't be fooled.