Internet Explorer 8 Beta 1 is a developer preview for web designers and developers to help prepare their websites for the launch of Internet Explorer 8. Some of the new features designed for developers include a developer toolbar and improved interoperability and compatibility. Internet Explorer 8 is designed to work in standard mode out of this box. However, Microsoft provides a way for users to browse the web in a way similar to Internet Explorer 7 by using the emulate Internet Explorer 7 button on the chrome.
Firefox 3 is based on the Gecko 1.9 Web rendering platform, which has been under development for the past 33 months. Building on the previous release, Gecko 1.9 has more than 14,000 updates including some major re-architecting to provide improved performance, stability, rendering correctness, and code simplification and sustainability. Firefox 3 has been built on top of this new platform resulting in a more secure, easier to use, more personal product with a lot more under the hood to offer website and Firefox add-on developers. Complete list of features are documented in the Release Notes.