Android 4.2 came with a number of goodies, one in particular was Miracast, which is basically a wireless display support feature. A confusion was created among alot of people on whether or not this feature is available on all devices running Jelly Bean 4.2 . Google has finally come out to clear this issue:
Just wanted to confirm that Nexus 4 is currently our only Nexus device that works with Miracast wireless display on Android 4.2. There was a reference to wireless display on our Help site for Nexus 10, but we’ve since removed that reference. Our apologies for any confusion that may have caused.
This means that only the Nexus 4 will be supporting the Miracast feature up till now, even though devices such as Galaxy Nexus, Nexus 7 and Nexus 10 all run on Jelly Bean 4.2. Technically they should support this feature, but till now they don’t. More information in the future would help us determine whether this feature will be available on the remaining devices as well or not. All those who still do not what Miracast is, maybe this video will help you understand it better.