Read the stories at http://www.waterstoneswys.com/
(You can pre-order the postcard book here -- limit of 2 per person.)
And the answer to my puzzled wondering of how on earth did Ms Rowling squeeze a reported 800 words onto that card? I was pushing to write a legible short story in about 300 words... was revealed. She turned it over. Fair enough. (Richard Ford also cheated and used two cards.)
There's a full report over at The Guardian:
As I said, you can read all the stories at http://www.waterstoneswys.com/. I've not read them all yet, but my favourite of the ones I've read so far was the Tom Stoppard "Idiomatic Farm" one. I was interested in the Atwood one when I read that,
Margaret Atwood appeared at the ceremony via videolink from Paris, wielding her celebrated LongPen - which reproduces handwriting remotely via sophisticated electronics - to handwrite her card "live". Her story, which she said she had struggled to condense into a form barely more capacious than a simple joke, provides a fresh spin on the Canute story, working in both domestic and ecological politics.Which it may well do, but I found it more or less unreadable and cannot tell if this is because of her handwriting or the way the LongPen reproduces it.
Mine went for about $2500 to someone who really wanted it and was thrilled to get it, so I am happy, and most of all I like the idea of people actually sending the stories to each other through the post. (Using, I hope, classic Hammer Horror stamps. Or better still, the Carry on Screaming stamp...)