He promised it was coming in yesterday’s interview with the Wall Street Journal, and now he’s delivering. Carl Icahn has sent an open letter to the Yahoo (NSDQ: YHOO) board, expressing “amazement” at the lengths the company went to to thwart Microsoft’s (NSDQ: MSFT) bid, specifically calling attention to (not surprisingly) the controversial severance plan. A full copy of the letter, which reiterates calls for Jerry Yang to go, was filed here with the SEC. Much of it is a pointed retread of some of Icahn’s latest statements, with some added rhetorical flourish. For their part, Yahoo’s Sue Decker told CNBC that the company continues to be in “engaged” talks with Microsoft on… something. Some highlights:

-- “Most importantly, Microsoft might never be able to trust a CEO and board who, while claiming to be negotiating in good faith, went behind their back and adopted a ‘plan’ which not only sabotages any Microsoft acquisition but went so far as to completely disable its own ability to rescind the ‘plan’ as long as Microsoft’s offer remains pending. Until now I naively believed that self-destructive doomsday machines were fictional devices found only in James Bond movies.” (Ed note: that has to be the highlight of the letter.)”

-- “Even more deceitful are Yahoo’s actions toward its own employees, for whom you claimed to have set up the “plan”. Management neglected to mention to these same employees that Microsoft in its proposals had earmarked $1.5 billion of retention incentives (representing over $100,000 per employee) meant to allay any employee concerns.”

-- “However, despite your actions to date, there is still some possibility that you can resuscitate a Microsoft offer for the company. The board can rescind the “severance plan” that is the largest impediment to a Microsoft deal. You currently can do this because Microsoft withdrew their bid 30 days ago. It is time for you to stop misleading your shareholders with respect to Microsoft.”