in first keynote of Google IO2012 Google announced new version of android OS series called jellybean, with some new features and some improved features
what new in android 4.1
Google now ( update in real time )
new feature called ‘Google now ‘ will update in real time will let you inform about things those matter to you . it will update you about your favorite places and locations and everything you are interested on or which is belongs to you , from your office to home

smarter search results
Google improved built-in search in JB ( jellybean)search smartly when you search for a person it will show you every single important related information about that person.

Resizable widgets
one of notable improvements Google announced in jellybean is resizable widgets when u drag or pin any widget on home screen JB will automatically resize  according to available space

offline voice typing 
now its possible to use voice to text offline , one of the major improvements in JB now you don’t have to worry about network when you are using voice to text and also Google improved accuracy

improved notification 
new notification area will show you more information than previous  notification center ,e . g .  now you can see not just missed call but time and contact name .

above are just few of changes and improvements of jellybean there are lot more . just wait for JB