Apple is not done launching new products and updates today. Safari 5.1 adds many new features, including a reading list, session resuming, and several Lion-specific features like multi-touch gestures, full screen browsing and sandboxing.Reading List and Safari Reader look to be very useful enhancements if you don't already use a service like Instapaper. In Safari you can now save articles to a list for reading later and also view articles distraction-free in a focused view.
Safari also finally can restore your tabs from your last browsing session and, giving Snow Leopard and Windows users a taste of Lion, you can also automatically restore your Safari windows with this Resume feature.
Many of the new features are only for those who have upgraded to Lion. These include multi-touch gestures support, full-screen browsing, sandboxing (automatically blocking malicious code from websites), a downloads popover, and better handling of HTML5 Canvas graphics.
Safari 5.1 is already included in Lion, but Snow Leopard or Windows users can download this update separately from Apple.