Android's growth just keeps climbing, with the latest number now over 700,000 activations per day, per Andy Rubin on Google+. That's an increase from 550k per day in July, 500k per day in June, and 400k per day in May. Basically, it's a slow and steady growth that's perfectly believable given Android's increase in marketshare this year.
Last month, Google revealed that over 200 million Android devices had been activated to date, double the number of devices from just six months earlier. The current pace of activations probably hasn't pushed Google beyond the 250 million iOS devices that Tim Cook touted in October, but at some point next year it's certainly possible that Android could surpass iOS in total number of devices activated.