Yahoo announced on Wednesday an agreement with Google for conducting a limited test of Google’s AdSense for Search service, delivering Google ads together with Yahoo search results. There is an extent to which this deal will take place however: the test will only be conducted for traffic from yahoo.com to U.S., will not include Yahoo’s network of publishing partners, it will last no longer than two weeks and will be limited to no more than 3% of Yahoo search queries.

In a statement released on April 9, Yahoo reinforced an idea Microsoft had already received in a letter: Yahoo is exploring different alternatives “to maximize stockholder value, including exploration of potential commercial business arrangements.”

Yahoo further stated that this test does not mean that Yahoo! will join the AdSense for Search program and the collaboration doesn’t necessarily extend to more than what they’ve already said: two weeks.

What could be the reason behind this step Yahoo took? Could it be another way to tell Microsoft: anything’s better than what you are offering…ever since Yahoo started saying No to Microsoft’s offer, it looks as if the alternative would be getting to know your rivals and making a deal with them, in this case with Google.

On April 7, Yahoo responded to a Microsoft ultimatum letter by accompanying it with a “Dear Steve” and saying that after taking into consideration the unsolicited proposal, they’ve reached the unanimous conclusion that it was not in the best interest of Yahoo and its stockholders to accept it.

“Our Board’s view of your proposal has not changed. We continue to believe that your proposal is not in the best interests of Yahoo and our stockholders […] Furthermore, as a result of the decrease in our own stock price, the value of your proposal today is significantly lower than it was when you made your initial proposal.”