HP has published the source code of Isis, the webOS Web browser. The company has also released the code of the browser's underlying HTML rendering engine, which is based on QtWebKit. The code is available from GitHub and is distributed under the permissive Apache license.
The webOS browser has been spun off into a new project called Isis, with the aim of making it cross-platform compatible. The browser's user interface is built with Enyo and is powered by QtWebKit, a port of the WebKit rendering engine that is part of the open source Qt development framework.
The Qt framework is owned by Nokia, but is used by other mobile platform vendors, including RIM and HP. One of the chief advantages of Qt is that it is highly portable. Using QtWebKit to supply the underlying HTML rendering engine for Isis will make it easier to bring the browser to additional mobile platforms.
Isis supports the Netscape Plugin API (NPAPI), which means that it is designed to support Flash and other browser plugins that handle embedded Web content. The browser itself doesn't come with a Flash implementation, of course, so it will only support the plugin on platforms where Flash is available.
For more details about the browser, you can refer to the Isis project website and the announcement on the HP blog. The code is available from GitHub.