Though Apple (AAPL) is suing many Android OEMs (including Google-owned Motorola), it has refrained from directly suing Google (GOOG) over the OS. And Google, while assisting in its partners' defenses, issued a cautious response to the Samsung verdict. What gives? It might be that the companies remain joined at the hip, in spite of all the enmity. Google needs its iOS search deal with Apple to maintain a dominant share of mobile search. And Apple doesn't want to lose Google's search payments, or its extensive iOS app support.