I beleive that they have always been around for a long time. However, with new technology springing up at a fast rate and gadgets are made in such a way that encourages home business, part-time jobs are gaining ground.,
Of course people have worked temporarily for other people throughout history as a way to earn extra money. But the corporate model we know today did not develop until the latter part of the 19th Century.
if compare to that time in human history, i would say its a new thing. But with developing communication technology and increased globalization part time jobs have become more numerous and better paying.