Apple isn’t as willy-nilly with their browser release schedule as Google is with Chrome or Mozilla is with Firefox. While Apple is hard at work making their browser better, you’re stuck with the aging public version. Sort of. Occasionally, they will release dev builds of Safari like the current Safari 5.2 beta. That’s great, but there is an easier and slightly nerdier way to get an early look at the latest and greatest in WebKit — Safari’s rendering engine.
If you head on over to the nightly build section, you’ll be able to download the latest build of the development branch of WebKit. This is a pre-made standalone app that takes the interface of Safari and swaps in the new rendering engine behind the scenes. You get to try out all the snazzy new HTML5 features, and your main installation of Safari isn’t even touched. You can always go back to using the boring old stable WebKit engine at any time. No hassle at all.
If you know what you’re doing, the full source code is available as well, so you can build your own tweaked version of WebKit right in Xcode. If you don’t know what any of that means, don’t worry. Just keep on using the latest stable version of Safari, and you’ll be happy as a clam. This is a nerd-only zone, I’m afraid.