Today Sony pushed live a PS4 System Software / Firmware v9.51 Update following the previous PS4 OFW revision, with the official PlayStation 4 changelog detailed below consisting of only the typical 'improves system performance' note. 
As always, DON'T UPDATE if you wish to use PS4 Game Backup PKGs via PS4 Torrents and Homebrew Apps whenever a new PS4 Jailbreak Exploit arrives... with some related Tweets from PlayStation 4 Scene developers below.
Download: PS4 Firmware 9.51 Update (US) / PS4 Firmware 9.51 Update (EU) / PS4 Firmware 9.51 Update (UK) / PS4 Firmware 9.51 Update (AU/NZ) / PS4 Firmware 9.51 Update (JP)
Below is the official 9.51 PS4 Firmware Changelog from Sony's page: PlayStation 4 system software update - PS4 9.51 system software features
Version 9.51
Main features in the system software update

Download: PS4 Firmware 9.51 Update (US) / PS4 Firmware 9.51 Update (EU) / PS4 Firmware 9.51 Update (UK) / PS4 Firmware 9.51 Update (AU/NZ) / PS4 Firmware 9.51 Update (JP)
Below is the official 9.51 PS4 Firmware Changelog from Sony's page: PlayStation 4 system software update - PS4 9.51 system software features
Version 9.51
Main features in the system software update
- This system software update improves system performance.