http://www.amazon.com/exec/obidos/tg/feature/-/154154/102-1377543-3248965
According to Bruce Davis, top exec at the Oscar shop, the Academy of Motion Picture Arts and Sciences:
Actually, nobody knows why the statuette is called Oscar.
There are three different stories:
The most common one is that a former executive director of the Academy named Margaret Herrick, on her first day coming to work for the Academy, saw the statuette on a desk and was supposed to have said, "Oh, that looks just like my Uncle Oscar." A reporter happened to be situated conveniently in the library and wrote in a column the next day that the Academy staff called the Academy Award the Oscar. But I've done some research on that, and she was never able to produce an Uncle Oscar. And besides, the one that she identified--who never came to town--was some sort of wheat farmer in the Midwest. Why a gold, nude knight would remind you of a wheat farmer is a little hard to figure.
Bette Davis claimed that she had given it the name when she received her first Oscar. She used to say that it reminded her of her then-husband, whose middle name was Oscar. She did at least have a husband named Oscar at that time, but no one called him Oscar. They called him Ham, and besides, it was later established that the nickname Oscar had been in currency prior to the time that she won her first Academy Award. Late in her career, she acknowledged that that story wasn't really true.
Xolumnist Sidney Skolsky claimed that he started calling it the Oscar one night under deadline. He got tired of writing "the Academy Award of Merit" and just picked "Oscar" as a synonym for "whatchamacallit." And actually, a column of his does seem to be the earliest reference to the use of the word Oscar in print. At this point, that's about as much information as we have. We know that the Academy did not use it for a number of years after it had achieved currency in Hollywood--they were a little prim about using a nickname. But by 1937 or so, the Academy itself had embraced the name.