Probably waiting on official driver support and certification. It may currently work with some hardware and software, but not others.
Please take you time, test it, and get it working right Apple before it is publicly released.
I believe that AdMob would do better being owned by Apple than Google, but I doubt that the FTC will get involved in this, but who knows?
If people are afraid of Google taking over everything on the Internet, maybe they should used BING, Yahoo, Ask.com, or some other search engine, and not support Google with their patronage or ad dollars.