In discussing quarterly results last week, AT&T revealed that they activated “roughly 900,000 connected devices” on their network in the past three months. That category includes 3G eReaders from Amazon and Barnes & Noble–along with netbooks, personal navigation devices, digital photo frames and all kinds of other gizmos. And would seem to include iPads as well. In answering an analyst’s question, the company said in just two months they activated 400,000 to 500,000 iPads alone. You can do the math on ereaders from there… Separately, Apple reported shipping 3.27 million iPads so far.