Tony who?

If Steve Jobs didn’t loom so large in Apple’s public persona — drawing the spotlight at every appearance — a lot fewer people would be asking that today.

Fadell was — and until he leaves at an as-yet undisclosed time for “personal reasons,” still is — the top engineer in a company renown for its engineering prowess. At Business 2.0, the now-defunct Time Inc. monthly, we ranked him No. 27 on our 2007 list of “50 Who Matter Now” in the world of business.

And when Fortune tried earlier this year to handicap who might be best equipped to replace Steve Jobs as Apple’s CEO, Fadell came in No. 2, after COO Tim Cook. Here’s how we described him then:

Tony Fadell
Title: Senior vice president, iPod division

With his American swagger and his hair bleached white, Fadell stood out at button-down Philips Electronics, where he led an in-house pirate operation designing Windows CE-based devices. It was there that he came up with the idea of marrying a Napster-like music store with a hard drive-based MP3 player. He shopped the concept around the Valley before Apple’s Jon Rubinstein snapped it up and put Fadell in charge of the engineering team that built the first iPod. Ambitious and charismatic (and no longer a bleached blond), he now runs the hardware division that makes two of Apple’s three key product lines: the iPod and the iPhone. (link)

Fadell will reportedly be replaced by Mark Papermaster, the top IBM executive who managed the company’s blade server business. IBM (IBM) sued Papermaster last week over a noncompete clause in his contract to try to prevent him from joining Apple (AAPL). See here.

In a press release issued Tuesday morning, Apple announced that Papermaster had been named senior vice president of devices hardware engineering, reporting directly to Steve Jobs.

According to the release, Fadell and his wife Danielle Lambert, a VP of human resources, “are reducing their roles within the company as they devote more time to their young family. Fadell will remain at Apple as an advisor to the CEO. Lambert will depart the company at the end of this year after a successor is in place.”