This is really starting to become very interesting now because it is being reported that Yahoo might be considering an alliance with Google in order not be be bought by Microsoft. There are reports that the chief executives of both companies have been talking about this after the Microsoft offer became known.
Yahoo is reported to be saying that the Microsoft offer undervalues Yahoo.
Ther are a lot more details about this possible alliance between Yahoo and Google. This article has them
Yahoo may consider Google alliance, source says | Technology | Reuters