The deeper issue, though, is that estimating tablet sales in this way is a little like trying to estimate global car sales by working out how many internal combustion engines are being made, and how many tyres, but not adjusting for motorbikes, cranes, outdoor generators or 18 wheelers. Lots of ‘tablet' chips and ‘tablet' screens do not actually end up in tablets.
There are a lot of good points in this piece, but this is a critical one. We know very little about what's actually happening with Android, except that it's propogating quickly around the world through devices far beyond its original scope. What's going to be interesting going forward is how the range of devices it can power evolves and how much data Google is able to mine from them.