I think patents had something to do with this, but what I really believe is that Google needed to something about fragmentation. I think Google was tired of thier software updates taking 4, 5 and 6 months to make it to the end user because the OEM's had to tweek it to be compatiable with thier propietary skins. This gives Google established distribution channels on the hardware side along with a terrific mfg'ing ability. What should happen is that Google phones will be released on more carriers carrying the stock Google OS. Software updates will come in a timely manner to more people and the other competing OEM's will need to compete on this new model. I see this as a win for the Android user base.
I really don't think this will happen. IF it does it will be long time down the road. I truly believe what Google said yesterday. Motorola Mobility will still run themselves as if they were not owned by Google. MM will call the shots on hardware and software. Google will be a silent owner. You will still see Motorola phones, not Google phones. At lest not any time soon. As I stated before, this does give Google the opportunity to release their own phones but again, this will be a long time down the road if it ever happens.
Also, there is a whole lot more to Motorola Mobility that just Smartphones. Google now owns their Cable Set Top box business, Xoom business, and cellphone accessories business. All this is part of Motorola Mobility.