Google's purchase of Motorola Android assets is the largest purchase ever (priced at $13 billion). Android is now used in over 150 million devices worldwide that's about 48% of the market share. Apple OS only owns 18% of the market. Google primarily made this move for the patents (about 7,500 pending). Manufacturing phones and other devices fits into Google's larger strategy; Apple owns the control of software, hardware, content, and network channels. Google manufactures software, and now with its purchase of Motorola, Google can have top to bottom control of hardware as well.
The patent issue is pretty much the major part of Google's deal with Motorola. Intellectual property rights are important because the negotiations are really a horse-trading game, and now, Google can come to some kind of common ground with the assets that it brings to the bargaining table. Now, it doesn't have to be a seller of revenue with a strong portfolio of patents, Google can offer more in trade, and have a less chance of lawsuits.
Google's trying to be like Apple; a controlled ecosystem, both competitor and protector at the same time. Tech blogs have been vague if this purchase of Motorola is a good idea or a colossal mistake. Microsoft and Nokia had the same questioning, and many asked at the time if Samsung/LG would see themselves at a disadvantage; these same questions pertain to Google and its Android licensees.
The cable/broadband business may be an after thought; Google cannot get Google TV to take off, but if it has Motorola it has instant access, some way into people's living rooms. Some are asking whether Google is looking to make it into "Tech War" as it extends partnerships with Broadband/Cable companions. Multiple connection devices are critical to people's day-to-day lives; realizing this, Google wants to be the brand behind those services, and Motorola has presence in all categories even in home security cameras. While this deal will go through some anti-trust review process, it will be a rather cursory glance instead of a prolonged and stringent review as in the case with AT&T and T-Mobile.