This is the first time that Jelly Bean has taken the lead from Gingerbread which has stubbornly stayed active even though it has been superseded several times. However Gingerbread's usage is in decline. At the beginning of this year Android 2.3 was running on just under half of all active Android devices and Jelly Bean had just a 10 percent share. Ice Cream Sandwich was popular with just under 30 percent usage. Fast forward six months and Jelly Bean is king having taken share from Gingerbread and Ice Cream Sandwich.
As for the rest of the field Android 2.1 and 2.2 are still used on 4.5 percent of devices while Android 1.6 Donut and Android 3.2 Honeycomb barely register at 0.1 percent. The reason for Gingerbread's longevity is likely because of its low system requirements. It is still possible to buy low end smartphones running Gingerbread today. Since it can run on devices with only 256MB of memory (or maybe even less) and doesn't need a very fast GPU then for emerging markets it is still a viable option. How long it will remain so is unclear, however the fact that Jelly Bean has finally taken the lead coupled with the fact that Android 4.x runs on over 61 percent of active devices, it seems that the end is nigh for Gingerbread.
Gingerbread served us well, but personally I won't miss it when it finally becomes extinct.