The message of the open, public letter sent on Sat 5th April is this:

"It has now been more than two months since we made our proposal to acquire Yahoo! at a 62% premium to its closing price on January 31, 2008, the day prior to our announcement. Our goal in making such a generous offer was to create the basis for a speedy and ultimately friendly transaction. Despite this, the pace of the last two months has been anything but speedy."

Link:
microsoft.com/presspass/press/ ...

And Yahoo! responds...

<< Our Board carefully considered your unsolicited proposal, unanimously concluded that it was not in the best interests of Yahoo! and our stockholders, and rejected it publicly on February 11, 2008.
[...]
At the same time, we have continued to make clear that we are not opposed to a transaction with Microsoft if it is in the best interests of our stockholders. Our position is simply that any transaction must be at a value that fully reflects the value of Yahoo!, including any strategic benefits to Microsoft, and on terms that provide certainty to our stockholders. >>

yhoo.client.shareholder.com/pr ...