Apple opened up a public CVS repository for WebKit, it made it possible to get the latest source, compile, and run it yourself. They even broke the steps to do so into easily digested step-by-step instructions. All one need do is get source and compile it.
You need to make sure that you have XCode installed and be comfortable with running Terminal commands. You don’t need to really understand them, just be able to type them in. If you’d like to avoid all that, there is a shortcut. Boyd Waters has put together and updated version of WebKit in an easy to use container called SafariOnAcid. The name is an homage to the fact that using the updated code, the Acid2 test passes. It’s worth checking out not only for standards compliance, but speed.
First, this is rolling your own WebKit, not Safari. Quite right. You continue using the existing Safari application just with the new version of WebKit. However, the real meat of Safari is WebKit.
This is old news indeed. I played with my own builds of WebKit but I stopped playing with it until someone mentioned SafariOnAcid (which is a very slick package). The speed increase is pretty terrific. Even with lots of tabs and windows, Safari stays extremely responsive.
This comment is terrific. It mentions NightShift, an automated way to get a nightly compilation of WebKit. I missed this on Daring Fireball’s Linked List. This is probably the best way to run with an updated WebKit.