The next stable release planned for OOo is 3.1.0 which will bring new features into OpenOffice.org Office Suite. For now, they have released a RC1 release which can be downloaded from here. Please note that this version is NOT yet considered stable as it *might* contain showstoppers and hidden bugs and it's intended for public review which will eventually become the final version of OOo 3.1.0.
The Release Notes will gives you detailed changes on this version, while this page will give you more readable documentation about new features in OOo 3.1.0.
My estimation about the final release is in the next 1-2 months unless something big happened during development cycle.