PlayStation 4 firmware update v3.55 is available now, but it probably doesn't do much. While we don't have access to the patch notes just yet – we'll add any information we can get hold of to the bottom of this post – it's assumed that this 300MB download is merely designed for stability. Perhaps it may pave the way for the eventual release of PS4 firmware update v4.00?
There's not much to get excited about for now, then, but your gaming shouldn't be interrupted if you stick your system in Rest Mode. It took us about 10 minutes total to download and install the update on a very average Internet connection, so there's nothing much to complain about here.
Update (13:00PM BST): The patch notes are out, and as expected they're not especially long. "Improves the quality of the system performance," is the only bullet point. Enjoy.