Apple Safari 3.1.1 is now available for both OS X and Windows. This update includes improvements to stability, compatibility and security.
On the security front, this security bulletin outlines the changes. It appears as if a vulnerability existed that could allow malicious sites to spoof URL headers or execute arbitrary code. There are two issues that specifically affect the Windows version of Safari, so users on both platforms should be sure to update to pach this problem.
some plugins, like Saft, will stop working after installing the update. Visit the plugin author’s homepage to download the newest versions as they become available.
You can download Safari 3.1.1 here