The significance of Service Pack 2 for Office 2007 is that it includes support for the OpenDocument Format, an open standard backed by many companies including IBM and Sun Microsystems but initially resisted by Microsoft.
Customers who download the service pack will be able to save documents in ODF and Adobe Systems' PDF, just like they would any current supported file format in Office. They can also set ODF as the default file format. Previously, people could use ODF through a separate plug-in that translates Office documents to ODF and vice versa.
Soon after ODF was approved as a standard in 2006, Microsoft created its own competitive file format, Office Open XML, for Office 2007. OOXML was later ratified by a standards organisation. But the creation of a separate, competitive standard angered ODF supporters.
Microsoft's lack of native support for ODF may have also been behind fines from the European Commission, which pushed Microsoft to support interoperability with other companies' products.
Office 2007 SP2 will also natively support PDF. Adobe initially opposed Microsoft's decision to add PDF to Office, but has since made PDF an open standard.
Microsoft won't support the standardised version of its own OOXML until Office 14, expected to be released next year.