Official OpenOffice.org releases do run on OS X, but are far from what Mac users would call "native." They require Apple's separate X11 service to run, are unable to use system menus, and don't integrate with core OS X services like printing, fonts, drag-and-drop, and the clipboard.
In addition to banishing those glitches, NeoOffice has some key features to trump even proprietary office suite competitors on OS X. Apple's iWork, for instance, includes only word processing and presentation apps, and Microsoft Office for the Mac hasn't been updated since 2004, which means Office for Macs is incompatible with recent Office documents from the Windows version. The new version of NeoOffice boasts Office 2007 compatibility.
We last reviewed NeoOffice for its 2.0 release in September. At that time, we described it as "head and shoulders above" the X11 OpenOffice.org alternative.