The departure of Brian Valentine, a 19-year Microsoft veteran before he left in 2006, has always been a bit of a puzzle. In August of that year, Microsoft management told his staff he was taking a new job within the company after shipping Windows Vista. A month later, he left for Amazon.com. Now, Amazon.com has cleared things up with a belated SEC filing: Microsoft lied to its employees. Here's the timetable:

Amazon.com sent Valentine an employment agreement, dated and apparently signed by Valentine on June 23, 2006. The deal called for him to get a $1.7 million signing bonus, a $150,000 salary, another $500,000 bonus, and 400,000 shares of Amazon.com (now worth almost $30 million). The contract called for him to start on September 11. Valentine surely told his bosses of this fact. And yet Microsoft did not announce his departure until September 5, less than a week before he started.

So why would Microsoft lie about Valentine's employment status? In July and August, Microsoft's programmers were on a death march to complete Windows Vista. Had they known that their leader, Valentine, had one foot out the door already, would they have worked so willingly on the project?

Lying to employees is one thing. It's routine and expected. But lying to shareholders is another. Given the importance of Vista to Microsoft's finances, shouldn't Microsoft have disclosed Valentine's plans to leave as soon as they knew about them? And assuming Valentine was complicit in the ruse, should Amazon.com's owners be similarly concerned?