That's the provocative suggestion made by Valleywag, based on an SEC filing disclosing the employment agreement former Windows exec Brian Valentine signed with Amazon.com.

Valentine was senior vice president of the Windows core OS group, but he was more than that -- he was the Windows engineering master chief. I used to think he was going to be Steve Ballmer's successor.

The SEC filing is juicy. After you get past the jaw-dropping dollars involved -- a $1.7 million signing bonus, a $500,000 bonus a year later, a $150,000 salary and 400,000 shares worth $31,840,000 at today's price -- the dates do jump out.

Valentine's offer is dated June 27, 2006. A few days later Microsoft told employees and the world that Valentine would transfer to another position in the company after Vista was complete. Maybe they were thinking of buying Amazon instead of Yahoo?

Microsoft ended up announcing Valentine's departure in September, more than two months after he'd received the offer from Jeff Bezos. It's not clear when they finalized the deal or when Valentine told Microsoft, but it had to be long before September.

I asked a Microsoft spokesman for its side of the story and will update this when I hear back.

UPDATE: Heard back from the spokesman, who declined to comment, reminding me yet again that the company doesn't comment on personnel issues.