It looks like Steve Ballmer is doing a little pre-spring cleaning.

Today, mega mobile network operator Vodafone announced the hiring of Pieter Knook, who spent the last five years running Microsoft's mobile business, and a handful of news organizations are reporting that at least two other top Redmond execs are on their way out the door.

According to News.com, Microsoft formally announces an "executive shuffle" sometime today. Also departing, the site says, are Steven Berkowitz, head of the company's online service unit, and Mike Sievert, who oversees Windows marketing.

In an email to News.com, Mike Sievert acknowledged he was leaving, saying that he plans to start his own business.

The Wall Street Journal says that Microsoft will also announce at least ten new promotions. Pieter Knook's post, the paper says, will be filled by Andrew Lees, currently a vice president in the company's servers and tools group.

Steve Berkowitz, the former CEO of Ask.com, joined Ballmer in the spring of 2006, and Mike Sievert, once a bigwig at AT&T Wireless, jumped aboard in 2005. This has led some to speculate that their departure is all about outside hires clashing with the "Microsoft culture". Which begs the question: If Microsoft has trouble bringing a mere two execs into the fold, how can it swallow Yahoo!, possibly the world's most popular dotcom? ®

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