"About Safari 4.0.5
(download button there goes to http://www.apple.com/safari/download/)
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

For detailed information on the security content of this update, please visit this site: About Apple Security Updates.

System requirements: Mac OS X 10.4.11, 10.5.8 or 10.6.1/10.6.2
(also available for Vista, XP and Windows 7)"

As I'm typing this (appx 5PM Eastern Thursday) the Apple security updates page didn't have it linked there yet but here's the doc with details About the security content of Safari 4.0.5.

• New OpenGL 4.0 aims to match DirectX 11
• Khronos Unleashes Cutting-Edge, Cross-Platform Graphics Acceleration with OpenGL 4.0
• Dolby bringing 3D voice chat to consoles, PCs/Macs
• OnLive streaming video game service launches in June with one huge catch
• Apple's iPad Could Kill The Mac
• Elgato Netstream shares the TV love
  
  Apps/Misc. Software Updates/Related Articles:
• GraphicConverter X 6.7
• RAW Developer 1.8.9
• Free App of the Day for Mar. 11th is Alexia
• Fling Free v1.3.3 (iphone/touch game)
• Google Reader Play: iPad-Friendly News Reader

• About the security content of Safari 4.0.5
• Apple TV: Using AirTunes
• iPod: Storing and reading notes
• OS X v10.6: Active Directory binding lost on network transition (.local domain)
• OS X v10.6, 10.6.1: Active Directory user may not be able to log in
• iPhone and iPod touch: Disabling digital camera notification in Windows XP
• iTunes Store: Unknown alert message when connecting (in Windows)

• Dell (With A Little Help From Amazon and Google) is Taking on iTunes
• Hands-On with the Crippled Stantum Slate PC
• Review of Seagate 2TB Barracuda XT (ST32000641AS) SATA6 Hard Drive
• GDC 2010: PlayStation Move vs. Project Natal - hands-on
• Audiophiles, try the Hifiman HM-801 ASAP
• GDC: Big Designers Find Satisfaction in Small Games
• Unreal Engine 3 (SDK) Adds Steamworks support
• Announcing Version 3.0 of Intel Graphics Performance Analyzers (Intel - posted Mar. 5th)