OpenOffice.org, a Sun Microsystems supported project, has been a free competitor to Microsoft Office for a number of years, but their support for OS X based systems lacked the integration with the Aqua user interface.
In fact, the current stable version (OpenOffice.org v2.4) requires X11 to display the office suite in OS X.
Fortunately, OpenOffice.org has announced the beta version of OpenOffice 3.0 that includes Aqua support for Mac OS X Intel computer owners.
While not the most important feature of an office suite, native interface will make for a more enjoyable user experience. Additionally, OpenOffice.org may gain support from Mac users now that the organization has contributed some attention to the Apple OS.

Head over to the 3.0 beta page if you’d like to download the latest version of OpenOffice.org v3.0 beta for the Mac with Intel Aqua capabilities.
As version 3.0 gets closer to a stable release it may be a solid option for Mac users when considering Microsoft Office or iWork.