The major problem of the Google Android OS is the fragmentation. People have always criticized the Android OS for its high-level of fragmentation. At the Google I/O conference, Google did say that it is trying its best to kerb fragmentation. The latest report from Android Developers suggests that the measures, which Google has taken, have surely been successful to a certain level. In this latest report, Android 2.1 has the highest market share at 50%. This is a 5% increase from the last time this report was published.
The above data was collected within a period of 2 weeks, ending on June 16, 2010. The data was collected by the number of Android devices, which accessed the Android market.
As it can be seen from the above chart, Android 1.6 and Android 1.5 still hold a major chunk of the market share. Hopefully, with the release of Gingerbread, and the updates of Android OS being slowed down to one per year, the fragmentation issue of Android OS will be eventually be solved.