Apple has opened up its Webkit software as an Open Source Project.
The software and documentation can be found at http://webkit.opendarwin.org/
Webkit is at the rendering core of Apple's web browser, Safari. The most recent builds have provided performance enhancements as well as compatibility (Acid 2 test). By providing the source, it allows developers to contribute to Webkit's progress. End users can build the latest version and use it with the current version of Safari to utilize the latest improvements in the web rendering engine.
David Hyatt discusses it in his blog.
The latest version of webkit is reportedly "substantially faster at loading Web pages and at handling JavaScript. It contains a number of additional performance improvements that went in post-Tiger."
