Apple said,
This update contains improvements to stability, compatibility, and security, including the following:
- Stability improvements for web applications that use WebSocket with certain proxy configurations
- Improvements to the appearance and layout of text with HTML5 ruby annotations
- A fix for an issue that could cause elements in frames to appear in the wrong place on pandora.com and other websites
The detailed security fixes is available at this page.
Snow Leopard (10.6.8) and OS X Lion (10.7) users should use Safari 5.1 instead.
UserAgent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-US; rv:1.9.2.19) Gecko/20110707 AlexaToolbar/alxf-2.13 Firefox/3.6.19
