You can read and article about her becoming vegan for 21 days here.
Also, she's blogging about her experience here.
Oprah writes in one of her blog entries:
Wow, wow, wow! I never imagined meatless meals could be so satisfying.
I had been focused on what I had to give up—sugar, gluten, alcohol,
meat, chicken, fish, eggs, cheese. "What's left?" I thought. Apparently
a lot. I can honestly say every meal was a surprise and a delight,
beginning with breakfast—strawberry rhubarb wheat-free crepes.
Posted by: The String Bean