Wikipedia has a great page on the sunscreen controversy.
Another interesting site that points to lots of various studies, including studies that show skyrocketing rise in melanoma in countries that have heavily promoted sunscreen.
Skin cancer rates have not increased for young men in the past 30 years, but have gone up dramatically in women. Lethal skin cancer rate rises in young women. Women, in my humble opinion, are much more likely to use sun screen and go to tanning salons.