Apple has posted Safari 4.1.1 and 5.0.1 to software update. Here are the details of the latest version:

New in this update:

Safari Extensions Customize Safari with features created by third-party developers Find extensions in the Safari Extensions Gallery, accessible from the Safari menu and extensions.apple.com

This update also contains improvements to stability, accessibility and security, including the following:

More accurate Top Hit results in the Address Field More accurate timing for CSS animations Better stability when using the Safari Reader keyboard shortcut Better stability when scrolling through MobileMe Mail Fixes display of multipage articles from www.rollingstone.com in Safari Reader Fixes an issue that prevented Google Wave and other websites using JavaScript encryption libraries from working correctly on 32-bit systems Fixes an issue that prevented Safari from launching on Leopard systems with network home directories Fixes an issue that could cause borders on YouTube thumbnails to disappear when hovering over the thumbnail image Fixes an issue that could cause Flash content to overlap with other content on www.facebook.com, www.crateandbarrel.com, and other sites when using Flash 10.1 àFixes an issue that prevented boarding passes from www.aa.com from printing correctly Fixes an issue that could cause DNS prefetching requests to overburden certain routers Fixes an issue that could cause VoiceOver to misidentify elements of webpages

For detailed information on the security content of this update, please visit this site: http://support.apple.com/kb/HT1222