Exclusive: Apple Global Marcom VP Allison Johnson Leaving Company

Allison Johnson, who has served as Apple’s vice president of worldwide marketing communications since 2005, is leaving the company, according to several sources.

The reason?

To co-found a new marketing and communications firm with another Silicon Valley communications luminary, Former Facebook PR exec Brandee Barker.

Sources said Johnson will begin work at the venture after negotiating her departure from Apple, which is likely to come sometime before the summer.

Beyond that, the details are slim. The new firm doesn’t yet have a name or a client list, although presumably answers site Quora and social buying service Groupon, two of Barker’s current clients, would sign on with the venture.

There’s no dearth of marketing and communications talent at Apple, but Johnson’s exit from the company is still notable.

She’s a seasoned and respected executive who came to Apple from Hewlett-Packard, where she managed public relations during the brutal proxy battle over HP’s acquisition of Compaq Computer. A former co-worker there once described her as “prime minister” of HP.

At Apple, Johnson has managed global advertising for some of the company’s most revolutionary products and the iconic ads for them. Those ads have been created by TBWA\Chiat\Day, which plays a powerful role at Apple.

Of course, this key part of Apple’s business is watched over closely by CEO Steve Jobs, to whom Johnson has reported directly.

In any case, Johnson’s departure is a loss for Apple, but quite a get for Barker and her new venture and a boon for Silicon Valley’s entrepreneurs.

In typical form, Barker said “no comment” when asked about the news. And an Apple spokeswoman declined to comment as well.