More on Facebook: Mark Zuckerberg was all about mobile. He noted 70% of mobile users visit Facebook each day, compared with 40% of PC users, and promised mobile monetization will surpass PC monetization. But the company admits PC ad sales are falling as mobile grows. COO Sheryl Sandberg talked up Facebook's ad targeting ability (aided by new products), and the ROIs posted by brand campaigns. She also claimed engagement for news feed ads is 8x higher than for right-hand column ads. Zuck says he doesn't want to compete against iOS and Android.