The new version of IOS 6.1.4 is available now as an Over the Air (OTA) update and via iTunes
iOS 6.1.4 is an 11.5MB update, which is not very large, there probably isn’t much else hidden away in this update.
The release notes indicate that there is an “Updated audio profile for speakerphone” whatever that means. Prior to the update I didn’t notice any issues with the speakerphone and I don’t see any change now that I have applied the update.
Perhaps there is an issue that affects enough people to prompt this small update exclusive to the iPhone 5 so there can’t be any harm done by installing this iOS Update.