IE9 Platform Preview 4 is available now at the IE9 test drive site. What's new in preview 4?
- Improved performance improvements across the product
- Increased support for standards and an improved Acid 3 score as a result
- Additional tests submitted to the working groups at the W3C
- Continue to address feedback from Connect
There's also a boatload of new demos on the testdrive site.
This is the last platform preview before the IE9 Beta and it's a good idea to start planning now for readying your sites for IE9:
- Test your site in IE9 Standards Mode
- Send IE9 the same standards-based markup your site sends other browsers
- Use feature detection, not browser detection to handle any cross browser differences in behavior or feature support
- Report issues on Connect if your site doesn’t look or work right, and you’re giving it the same code as you’re giving to other modern browsers
- Consider the experience for IE9 Beta users if you find that sending the same markup creates more issues than you can resolve in your production site
- Take advantage of HTML5, CSS3, SVG, DOM, ES5, and more…
Lots more detail on this (and IE9 Preview 4 generally) on the IE Team Blog.
Note: There's no need to uninstall earlier preview builds, Preview 4 will install over the top quite happily.