Few things come to my mind when I read this:
1) Several hundreds of thousands of Android phones are discarded/traded/ebay'ed every day to make way for the new devices. Otherwise a year from now, assuming that rate doesn't dwindle down, about 4-5% of the entire world's population use Android smartphones. If we count only 30% of that activation number as being true for US (210,000 Android phones a day), that means about 25% of entire US population, regardless of age or income or social status, uses Android smartphones in a year. Not even counting the current base. Does that sound reasonable?
2) What happens if I go through a phone, find it defective and return it, then find the replacement phone defective and return that one as well? 3 strikes for me. 2 devices probably go straight back to factory. Not to imply anything, but that can drive "activation" number way up.
3) What happens if I change my phone's identification by installing a custom ROM? Does that count as well?
4) If I obscure my IMEI number while trying to unlock the phone, the result is that the phone is still usable on its original carrier, but can no longer be unlocked without first fixing the IMEI. But it's still perfectly capable of accessing the Market and all of Google services. Does that one count as well?
Number 2 can happen with any other platform (especially for iOS), so that's a more reasonable explanation to me. Number 3 and 4 can definitely happen, and especially more so as people flash ROMs daily. I don't know about others, but I can flash my Captivate to a Vibrant ROM and then to a Galaxy S ROM and at each step with 2 different IMEI numbers if I were to try to unlock the phone and fail in the process, so that alone accounts for 6 phones without any exchange.
Not to dispute the number, but to say that's the actual count of real phones, I just don't buy it.