Back in January, HP pledged to open source
the floundering webOS
by September 2012, and wouldn’t you know it, the company delivered on its promise.
The webOS beta is now available, and it includes 54 components (under the Apache 2.0 license) and two separate build environments--one is a desktop build, and the other is an OpenEmbedded build designed to be ported to various other devices and includes an ARM emulator, cross-compiling support for embedded platforms, and support for multiple hardware architectures.
In addition to previously-released features including browser and browser server, platform portability layer, system policies, DB8 database service, Luna-service2, and more, the new beta features a System Manager and a handful of core applications such as accounts, calendar, clock, contacts, email, and memos.
If you want to get involved with the webOS development community, you can learn more here