Daringfireball was quoting WIRED's Fred Vogelstein:
"The true comparison is between Android and iOS, Apple’s mobile operating system. Android’s activation numbers are not device dependent. Apple’s shouldn’t be either. If we are going to truly compare the two mobile OSs we need to include sales of iPads and iPod Touches. Add them into the mix and the data shows that Android is catching up but still isn’t close."
Of any single device? I'm not sure, all combined maybe. The B&N nook alone is probably the most common one but probably only a half million units sold. So even all combined probably not.
The nook has such little power that to call it "Android Powered" is a gross misuse of the term. Yes, you can downgrade the firmware, root the device, and upgrade it, but the web browser is still god-awful and I didn't see any good third party apps.
For an e-book reader, with the option of playing Chess and MP3s, its top-notch. But right now, the ability to run apps on it is more theoretical than practical.
"The true comparison is between Android and iOS, Apple’s mobile operating system. Android’s activation numbers are not device dependent. Apple’s shouldn’t be either. If we are going to truly compare the two mobile OSs we need to include sales of iPads and iPod Touches. Add them into the mix and the data shows that Android is catching up but still isn’t close."
http://daringfireball.net/linked/2010/07/30/vogelstein