Android Market tracker is currently showing 200,000 products in the portal. It also records over 103 new downloads per second.
It's a speedy rate of expansion, though still some way behind Apple's 3m apps total. AndroLib also shows 2.5 billion downloaded apps on Android, against Apple's 6.5bn.
These estimates suggest Android could take the downloads top spot by 2013.
Of course, there are many arguments against this. Android is still a messy and fragmented OS with multiple iterations and tweaks by operators.
In Checkout, it also lacks a popular billing system which has persuaded some developers to either ignore the OS or choose ad-funded versions of the products only.