From a Google Blog - New features for the Google Docs Viewer
Google Docs Viewer allows users to quickly view PDFs, Microsoft Word documents and PowerPoint presentations online by viewing them in the browser without downloading them locally.
New files supported:
Microsoft Excel (.XLS and .XLSX)
Microsoft PowerPoint 2007 / 2010 (.PPTX)
Apple Pages (.PAGES)
Adobe Illustrator (.AI)
Adobe Photoshop (.PSD)
Autodesk AutoCad (.DXF)
Scalable Vector Graphics (.SVG)
PostScript (.EPS, .PS)
TrueType (.TTF)
XML Paper Specification (.XPS)
