Eager to frustrate Microsoft’s attempt to takeover Yahoo in any ways possible, Google has agreed to help Yahoo by participating in an unusual test that will gauge how much advertising Google can sell for Yahoo, its struggling rival. Talk about strange bedfellows! But the numbers will be interesting to watch.

Not sure what final form of co-operation framwork will take but I guess it will incorporate both yahoo and google elements. Hopefully the partnership will be enjoy best of both worlds.
If this happend you know that in the end google would completely buy out yahoo but keep it branded as yahoo (owned by google), would be such a kick to microsoft but saying that unless google release a good OS then Microsoft still sits on top of the world.
It would be so tragic for Yahoo if Google is eating up Yahoo; Yahoo is just going from the fire (Microsoft)straight into frying pan (Google).