Clinton made a surprise trip to California Wednesday. (Photo by Yana Paskova/Getty Images)

She may be on a hiring spree ahead of an expected presidential campaign launch in April, but that hasn't kept Hillary Rodham Clinton off the lucrative paid speaking circuit.

On Wednesday, a day after her news conference at the United Nations to address the controversy over her e-mail practices, Clinton made an unannounced trip to California, where she delivered a paid speech to executives at eBay, the Silicon Valley e-commerce giant.

The former secretary of state was paid for her appearance, according to a source familiar with the arrangement. Clinton's representatives as a practice do not disclose her fee, but she typically makes $200,000 to $300,000 per appearance, with visits to the West Coast usually commanding higher payment than those closer to her homes in New York and Washington.

Clinton also gave a paid speech a couple weeks ago in California, where on Feb. 24 she addressed "Lead On," a Silicon Valley women's conference. She will give another paid speech on March 19, addressing camp counselors and other educators at the American Camp Association's conference in Atlantic City, N.J.

At eBay, Clinton's appearance was a "surprise" to the 500 company executives who had gathered for eBay's Women's Initiative Network Summit. It was not announced publicly and closed to the media. Her California trip only became public when USA Today published a story early Thursday morning about the eBay speech.

According to a source familiar with the event planning, Clinton's team asked that the speech be opened to the press, but eBay officials wanted to maintain the element of surprise and therefore did not want television cameras and reporters present. The USA Today reporter gained access to the event because he was working on a story about an eBay executive and was allowed to attend, according to the source, who requested anonymity to discuss internal deliberations.

Clinton has ties to eBay. Chief executive John Donahoe’s wife, Eileen Chamberlain Donahoe, was an appointee at the State Department under Clinton. She worked as U.S. ambassador to the United Nations Human Rights Council in Geneva, Switzerland.

Clinton's speech focused on women's equality in the workplace, a theme she has highlighted in her public remarks for several weeks now. She gave a 20-minute speech and then answered questions from Beth Axelrod, eBay's human resources senior vice president. The issue of her use of a private e-mail server to conduct State Department business did not come up, according to USA Today.

The newspaper reported that Clinton said a diverse workplace "isn't just the right thing to do, it's the smart thing to do for eBay's bottom line. Inclusivity in the 21st century is a recipe for success. It brings fresh ideas and higher revenues. And in our multicultural country, building a more diverse talent pool isn't a nice-to-do, it's a must-do."

The question-and-answer session topics included Clinton's tips on parenting as well as doing business in Russia and China, which Axelrod noted were difficult markets for eBay, according to USA Today. Clinton noted that she had recently spent time with Jack Ma, a billionaire entrepreneur who founded and runs Alibaba, a group of Internet-based businesses, and is considered China's richest man.

"With respect to Russia, corruption is a cancerous problem for many businesses," Clinton said, according to the newspaper. Talking about China, she noted it was one of the biggest questions she faced as secretary of state. "I'm quite sober about our companies competing [in China] going forward," she said, noting that FedEx is losing many of its Chinese locations due to new government regulations.