If you love to have the latest software for your Mac, it doesn’t get any fresher and tastier than the nightly WebKit, the open source browser engine in Safari.
WebKit is an open source web browser engine. WebKit is also the name of the Mac OS X system framework version of the engine that’s used by Safari, Dashboard, Mail, and many other OS X applications.
If it looks like Safari, works like Safari, feels like Safari, is it Safari? No, it’s WebKit; what Safari will be tomorrow.