Mozilla has released the third beta for Firefox 4.0 on August 11, 2010. This release is being made available for testing purposes only, and is intended as a preview release for web application developers and the testing community.
Firefox 4 Beta 3 includes several major features and improvements – by testing them early we’ll be able to respond to your feedback for future versions of Firefox. The included Feedback Add-On that helps you let us know what you think about the new features and technologies in the beta.You can read more about this release on the Mozilla Blog, or at any of the following links:
Source: Mozilla Developers News