Internally, Google Engineers work "by dessert" [1], the version numbers are decided by someone further down the product pipeline. With an instance like this, the developers most likely made a number of updates to the same branch of the OS (Jelly Bean), that someone in marketing/product management felt were significant enough to warrant a new 4.x number. At the end of the day though, it's still the same Jelly Bean core, so the next desert is reserved for another actual OS branch.

[1] - I believe JBQ said this to the media once, but I can't find the source now.

2.0 & 2.1 were both eclair, and 3.0 & 3.1 were both honeycomb.

The fact that they didn't change the product name indicates that this is a fairly minor update.

There was also a 3.2 Honeycomb release.

Android updates are named after things you might want to eat. OS X updates are named after things that might want to eat you.

It's just a point release. There's been at least one for every version since Eclair except Froyo.

http://developer.android.com/reference/android/os/Build.VERS...