This update is recommended for all Safari users and includes improvements to performance, stability, and security including:
– Performance improvements for Top Sites
– Stability improvements for 3rd-party plug-ins
– Stability improvements for websites with online forms and Scalable Vector Graphics
– Fixes an issue that prevented Safari from changing settings on some Linksys routers
– Fixes an issue that prevented some iWork.com users from commenting on documents
For detailed information on the security content of this update, please visit this site: http://support.apple.com/kb/HT1222.