Apple users, it's here -- the final, stable, built-for-the-regular-public version of iOS 8 has arrived. Back up your stuff so you don't lose everything, and then go get that fresh new software!
For your over-the-air update, just go to Settings > General > Software Update to download the latest OS. We will also post direct download links from the iTunes store when they become available. The shiny new software works on iPhone 4S or newer; iPad 2 or newer; iPad Mini and Mini 2; and the iPod Touch 5G. But please, think twice about installing it on your world-weary 4S.
iOS 8 packs a lot of cool tricks that are tailored to the iPhone 6 and 6 Plus's new features, including the NFC-powered Apple Pay and that handy new interface that puts all the icons within reach, even on those bigger and bigger still iPhone screens. But there's plenty of handy new additions that will rev up the iPhone you've already got: Healthkit, Continuity, Messaging enhancements, Touch ID integration in a wider list of apps and more. Read up on the full capabilities of iOS 8 here, and hopefully you'll hit "download" before the line for iOS 8 gets too long.
Update: Commenters note that the iOS 8 file lists a space requirement of up to 5.8GB to download, though the file itself is only 1.1GB. By comparison, iOS 7 required about 3.3GB to download.