The first shots of Android 4.3 allegedly running on an actual phone have been posted online. Taken during the Thailand Mobile Expo 2013, they are of a Google Nexus 4 and the About screen clearly shows the term Android 4.3 listed.
Droid Life says it also displays a new build designator, JWR45B. And as the kernel is dated at 14 May, the Android site believes this is the real deal.
The other pictures show the camera in action - with a slightly modified interface - and a screen of just the Jelly Bean Easter Egg that can be found in the About section too. The Android version on that is listed as Android 4.3 as well, and it seems to confirm that this update will continue to be named Jelly Bean, not Key Lime Pie.
The pics were posted to the xda-developers forum and, if genuine, could be an indication that Google is going to announce the update and any new features. It was expected to do so at the recent Google I/O, but there was nary a whiff of it.