New MS Office saves stuff in XML format (.docx etc.) and OOo is unable to open the files without some help. I have successfully installed helper apps on Ubuntu to open these files (only tried a simple docx file so far); I'll explain how below.

Novell has released OOo extensions for this purpose. Here's the copy from this page:

The OpenXML Translator provides support for opening and saving Microsoft* OpenXML-formatted word processing documents (.docx) in OpenOffice.org.

The odfconverter-1.0.0-2.oxt file works only with Windows, and the odf-converter-1.0.0-5.i586.rpm file works only on SUSE® Linux Enterprise, SUSE Linux, and openSUSE. On both platforms, the OpenXML Translator works only with the latest Novell® edition of OpenOffice.org.

Using alien on Ubuntu I installed the rpm thusly:
$ sudo alien -ct odfconverter<version>.rpm
which results in a tgz bundle. Unroll it and enter the directory.
Then:

$ sudo cp usr/lib/ooo-2.0/program/OdfConverter /usr/lib/openoffice/program/

$ sudo cp usr/lib/ooo-2.0/share/registry/modules/org/openoffice/TypeDetection/Filter/MOOXFilter_cpp.xcu /usr/lib/openoffice/share/registry/modules/org/openoffice/TypeDetection/Filter/

$ sudo cp usr/lib/ooo-2.0/share/registry/modules/org/openoffice/TypeDetection/Types/MOOXTypeDetection.xcu /usr/lib/openoffice/share/registry/modules/org/openoffice/TypeDetection/Types/

**note that I stole these instructions from here.

I will try this on a lab machine for the next build. The difference is that Novell has a Windows-only package that can be installed from within OOo's package manager.