Android 4.1 Jelly Bean adoption rates grew by 1,500% in 2 months
Phandroid

Based on research data gathered by mobile ad network Chitika, Android 4.1 Jelly Bean grew the fastest among all flavors of Android in the span of only 2 months. The rate of adoption for Android 4.1 Jelly Bean grew up to a cool 1,500%. The great majority of Android devices out in the world right now still work with the Android 2.0 framework, though if things keep up, it won't be long before those on the 4.0 framework start to show good numbers.

What Else You Need To Know

  • Android 4.1 Jelly Bean's overall market share is expected to rise even more with the release of newer devices running the latest version of the Android software by default.

Other sources

In an ideal world, current device models would be quickly updated to the latest OS build, but the problem dubbed fragmentation, or the existence of dozens upon dozens of differently specced phones with unique hardware running on a multitude of carrier networks, has created more than its share of stumbling blocks. - Kevin Krause, Phandroid  
The Next Web
Two months in, Jelly Bean only represents 1% of all Android traffic  

Jelly Bean was at just 1.2% in August, according to Google’s latest numbers.

Other
Jelly Bean only represents 1.2% of Android web traffic, anyone surprised?  

Jelly Bean won’t be the one to fix Android’s fragmentation problem. As Chitika puts it: “With Jelly Bean’s rollout to only a select set of devices, it’s unlikely that this version of Google’s operating system will generate adoption rates to put a dent in this ongoing issue – top of mind for mobile app and Web developers.”

BGR
Android 4.1 Jelly Bean usage grew 1,500% in just two months  

While the percentage of users with Jelly Bean installed on their devices is still incredibly low compared to 57% percent share of devices running Android 2.3 Gingerbread, it’s likely that figure will grow even quicker once more devices capable of running Jelly Bean arrive.

Phandroid
Jelly Bean adoption grew by 1,500% in first two months, outpaced previous Android versions
Android Community
Android 4.1 Jelly Bean user base grew 1,500% in two months  

Then again, Jelly Bean early adoption rates are a tad higher than Ice Cream Sandwich’s rates.