Apple has released iOS 6.1.4 for the iPhone 5 and it is available for download now. This update is a minor one and pertains to an updated audio profile for speakerphone. This update is only available for the iPhone 5 at the moment and not for any other iOS device. The update itself is only 11.5mb so it really is only minor changes in this update.
The speakerphone profile that this update is based on sets the parameters for the quality of audio produced and Apple hasn't specified if anything else is included in this update in their release notes. One or two tweaks may of course have been sneaked into this update and will only be what Apple deem necessary.
If you have an iPhone 5 running on iOS 6.1.2 or earlier and you are jailbroken or you want to jailbreak in the future, you should steer clear of this update. The jailbreak community has said on numerous occasions, that all new discoveries related to a post iOS 6.1.2 jailbreak are being saved for a more significant release in the future, so do not update if you want to install Cydia or jailbreak you device.
Apple are said to be working on building iOS 7 and this minor update probably just goes to show how few staff are working on iOS 6 at this point. From what we have been hearing, the skeuomorphic elements within the company's mobile ecosystem are set to be wiped out, with flat, clean surfaces taking their place. This has already seen Apple borrowing staff from the OS X team to help get the preview of iOS 7 ready for WWDC 2013. We are expecting some big changes after several mundance iOS released and all of us here can't wait for the big unveiling.
In the meantime, if you don't have a jailbreak and aren't planning on jailbreaking your iPhone 5 and you want to update to iOS 6.1.4 to reap the beneftis of the updated speakerphone audio profile all you have to do is use the software update feature that is located in your device's settings app or plug your iPhone 5 in and update it via iTunes.