From the description:
3.0a1 (26 July 2014) Win 32 / Win 64 / Linux 32 / Linux 64 / Mac OS X.
The revisions cover incremental changes between releases, and are especially important to read for pre-releases.
From the revisions:
Kicking off the 3.0 release process. The focus for Processing 3 is improving the editor and the coding process, so we’ll be integrating what was formerly PDE X as the main editor.
This release also includes a number of bug fixes and changes, based on in-progress Google Summer of Code projects and a few helpful souls on Github.
Please contribute to the Processing 3 release by testing and reporting bugs. Or better yet, helping us fix them and submitting pull requests.
In case you are unfamiliar with Processing:
Processing is a programming language, development environment, and online community. Since 2001, Processing has promoted software literacy within the visual arts and visual literacy within technology. Initially created to serve as a software sketchbook and to teach computer programming fundamentals within a visual context, Processing evolved into a development tool for professionals. Today, there are tens of thousands of students, artists, designers, researchers, and hobbyists who use Processing for learning, prototyping, and production.
Enjoy!