From Reddit:

The "we Can Do It!" poster that is associated with Rosie the Riveter was originally an obscure anti-absenteeism poster intended to boost morale of the workers in a metal-stamping factory in Ann Arbor, Michigan. The model for the poster is likely Geraldine Hoff Doyal, a cellist who worked at the factory briefly.

Rosie the Riveter was a cultural icon during the war, being the subject of a popular song and a Saturday Evening Post cover by Norman Rockwell.

The two became conflated in the 80's as feminist groups adopted the poster as a symbol of equality and a reminder of the accomplishments of women during the war. While the "We Can Do It!" poster is not, strictly speaking, a Rosie the Riveter poster it has readily been adopted as such in modern day as "Rosie" was a catch-all for the women who took on fabrication jobs during the war.

This poster was created by American graphic artist. J. Howard Miller. In 1941, Miller’s work came to the attention of the Westinghouse Company and he was hired to create a series of posters to sponsor the company’s War Production Coordinating Committee. This poster is commonly called Rosie the Riveter, however at the time of the poster’s release that name wasn’t associated with the picture. That came a year later later when a popular patriotic song called “Rosie the Riveter came out. The poster became a symbol for women who produced war supplies and took new jobs replacing the male workers who were in the military. Miller based the “We Can Do It!” poster on a United Press International picture taken of Geraldine Doyle working at a factory. Ironically, Doyle only lasted two weeks on the job before quitting because she feared a hand injury would prevent her from playing her cello. The poster did not become widely known until the 1970s and 80s when it began to be used by advocates of women’s equality in the workplace.

Interesting Fact: Geraldine Doyle, who was the inspiration behind the now famous poster, died last year at the age 86. Doyle didn’t know she was the model for the poster until 1984, when she came across an article in Modern Maturity magazine, now known as AARP, which linked a photo of her to the poster.

For more: http://listverse.com/2011/06/21/10-interesting-facts-behind-popular-posters/

From Imgur:

what about the rest of the story?  wasn't she bullied off reddit for this?

You're right that Reddit bullied her for posting. (Read down the thread.)

She ended up deleting her Reddit account because commenters were mean about her posting for attention.

Meanwhile, Imgur has nothing but love for her.

And that, essentially, is the difference between Imgur and Reddit.