LibraOffice is an offshoot of the OpenOffice open source project that split-off from the original project because of issues that they had with it (more information).
If you're looking for a free open source multi-platform office suite, this is one of the better ones. I never found it as powerful as Microsoft Office, but if you're looking for a free office suite of tools this is the one I like to use.
betanews reported: "The Document Foundation released LibreOffice 4.0 FINAL. The open-source, cross-platform productitivty suite, which is based on OpenOffice, has evolved to the point where the developers are happy to assign a major new version number.
Version 4.0 includes a number of relatively minor new features, but the big changes will come under the hood, marking the first radical development in the program’s API since the app it was built on -- OpenOffice -- was first released. Other changes include support for Firefox Personas, integration with CMS and online storage providers, plus support for importing both Microsoft Publisher and the latest VISIO documents." (read the rest of the article)