nobody really knows. but a few weeks ago, the OS version numbers were released, and a few sites extrapolated based on those numbers. since at that time, onle one phone, the nexus s, was on gingerbread, and the number was 0.3% of android phones were on gingerbread based on the numbers.
so from that, knowing that 300k phones are sold each day, and the nexus s has been out for 1.5 months, only about 40k nexus s phones were purchased.
this is highly subjective, but you get the idea.