The widow of the late Steve Jobs has joined the Forbes Rich List, becoming the 28th richest person in the world.

Laurene Powell inheritance of the Apple cofounders fortune, estimated to be US$11bn, makes her the wealthiest woman in Silicon Valley.

The news comes days after pre-orders of Apple's new iPhone 5 topped two million in just 24 hours of trading, more than doubling the past record of the previous model.

Powell, a newcomer to the list released today, is described by Forbes as:

“A Stanford business school student when she met her husband, Powell once started a natural foods company and was an angel investor in SocialCam, a mobile video-sharing startup bought by Autodesk for $60 million in July.

"She also founded 2 nonprofits: College Track, designed to ensure admittance to and graduation from college for underserved students, and the Emerson Collective, which works with entrepreneurs on immigration reform, social justice and conservation.

"She was recently appointed to Stanford's board of trustees.

Other notable tech people making their debut on the esteemed list include Twitter and Square cofounder Jack Dorsey with an estimated worth of US$1.1bn.

Tech giant Bill Gates was listed as the wealthiest American for the 19th year in a row, with a fortune of $66bn.