Neowin posted a news story that Microsoft Office 2007 SP2 will be released later today

Service Pack 2 includes some significant changes, including built-in ability to save as ODF & PDF formats, improvements to Outlook's performance and calendar reliability and significant bug fixes for charts in core Office applications. It is also a rollup of all fixes that have previously been released for Office 2007 products.

The company has published a support article detailing the various fixes and improvements contained in the SP2 update. According to the document there are improvements in the following areas, to name but a few:

Outlook responsiveness
More reliable Outlook calendar updates
Search reliability
RSS improvements in Outlook
Better .pdf/.xps output fidelity
Improves the charting mechanism in Excel 2007
Provides faster file resaves in PowerPoint 2007

Microsoft Office 2007 SP2 due today