Office "12" will support a native Save as XPS feature in Word, Excel, PowerPoint, Access, Publisher, Visio, OneNote and InfoPath.
What is XPS?
XPS, or the XML Paper Specification, is Microsoft's new electronic paper format for exchanging documents in their final forms. This Office feature provides a one-way export from Office client applications to an application- and platform-independent, paginated format.
Unlike the Office Open XML Formats, XPS does not attempt to capture the full structured richness of an Office document. As an electronic paper format, it is all about a high fidelity representation of the output only. Because of this, creation of an XPS document from Office is a one-way, export operation.
Why would I want to use XPS?
XPS is an electronic paper format built around the same Open Packaging Conventions document structure as the new Office file formats. This means a Zip container and XML content. As such it plays well with other technologies like Microsoft Information Rights Management (IRM) and is open to developers to read and write, using APIs in the Windows Presentation Foundation or any other tools capable of working with XML and Zip. This openness makes XPS convenient for a range of scenarios in which it is useful to inspect or modify the contents of the "paper" programmatically.
How does this relate to the XPS print driver?
The Windows Digital Documents team is delivering a print driver with Windows Presentation Foundation that will enable all applications that can print to create XPS files. The support for XPS output in Office "12" goes beyond what is typically passed to a printer, including the supporting information to enable, for example, working hyperlinks, searching, efficient representation of transparency and gradients, accessible documents, and document rights when the source document has restricted IRM rights.
So Office is supporting two electronic paper output formats
How do I view an XPS document?
With an XPS Viewer, of course. You likely don't have one of these yet, but Microsoft is committed to delivering viewers for Windows Vista and downlevel versions of Windows, with Windows Presentation Foundation, and directly or through partners, for a range of other platforms. Of course, if you don't like any of these viewers, the format is open and documented and you could always write your own.