If our review of Android 4.1 Jelly Bean wasn't comprehensive enough for you, Google has posted up a big, bullet-filled page with all the stuff it has added in since 4.0. All the big name features are here, but by reading through point-by-point you can find small details that might matter to you. If you try, be prepared to see apps described by "buttery," discover optimizations to how SMS and Google Talk work, and pay special attention to an intriguing mention of "Support for USB audio docks, shipping later this year."
Notably, Google separates off the "Google experience on Android" from the rest of Android 4.1 — and that's where Google Search and Google Now reside. The two are separate things, if you weren't aware, with Google Now referring specifically to the intelligent cards that pop up as you go about your day.
Finally, there are also several instances of apps that have been optimized for 7-inch tablets — for reasons which should probably be obvious to everybody. Hit the source link for a look at your Android future (whose arrival is still TBD), but don't miss our full look at Android's past to see how we got here.