whopping 57% of Android users are still using a device running on Gingerbread and this is a build of Android that dates back to 2010. Even with the huge increase in Jelly Bean users over the two months ended in August, the increase is coming from a small base which means that the same issues continue to work against Android users. Slow updates, manufacturers deciding not to update fairly new devices and long testing times are problematic.
Unlike iOS, which updates basically one phone and one tablet (admittedly across a few generations), Android updates need to work on different phones and tablets made by different manufacturers. And even a stock Android model like the Verizon version of the Samsung GALAXY Nexus has yet to be updated to Android 4.1.
source: Chitika via Phandroid