In one way or another, the 1 billion plus downloads do point to the number of Android users are out there. Google relies on unique accounts that have downloaded the app, instead of individual downloads which would most probably result in a far higher number. Basically, at least a billion Gmail accounts have already downloaded this particular app at one point in time or another, and this trend does not seem to stop. Now all that we need to do is to wait for the number of installs to breach the 5 billion mark, and I would not sit up all night waiting for that to happen as it is going to take some time more despite the popularity of Android worldwide.