Owners of the Google Play Edition versions of the Samsung Galaxy S4 or the HTC One will want to actively check for updates. Google just launched the newest 4.3 version of Android Jelly Bean for those devices over the weekend. Here's a quick quote with the major changes you will see on the devices,

Major changes seem to be increased icon sizes on the widget panels as shown above on both HTC One and SGS4, and working IR on the HTC One, thanks @nkj. Bluetooth tethering has also been added to the SGS4 GPe, meaning I can finally use that device with Google Glass and my Parrot Asteroid Smart head unit, which both require Bluetooth internet tethering to work. The solid black background on the SGS4 GPe in settings and other places has also been replaced with the stock Android 4.x gradient.
Sound off if you are one of the lucky owners of one of these devices who have received the update already.

Source: AnandTech