It took Apple three weeks to address the most problematic bugs in Leopard. Good job ! The security contents of the update are detailed here. See also the relevant TidBits link in the feed box below.
Update: Heise Security's opinion on the fixes.
Safari 3.0, shipped in 10.5, includes a WebKit update that will certainly improve our Web experience. The Ars Technica article gives an interesting perspective on the WebKit market and WebKit.org gives a technical review that highlights the main new features. This new version of the WebKit is available in Leopard and in the latest Tiger update (10.4.11) released yesterday.
If you make a search in TextEdit now, you'll see that the search results are highlighted as they are in Safari. Much easier to see the searched string !