I seem to have become a top search engine result for queries for a Microsoft Publisher Viewer. The bad news is that there is no Microsoft Publisher Viewer. The good news is that we have a better solution to this problem coming with Publisher 2007. Every time we look at doing a Publisher Viewer, we run into the problem of how to get enough distribution that people could reliably share Pub files and count on the viewer being available at the other end. We also think there is a limit to the number of single-application viewers that people want to download. Instead what customers have long been asking us for is a way to get Publisher content into application-independent viewable formats.
For Publisher 2007, we plan to make available free add-ins from Microsoft that enable the generation of both PDF and XPS files from Pub. PDF viewers are widely deployed today, and XPS viewers are starting to become available. As they do for earlier versions of Publisher, we also expect that third parties will offer their own solutions for capturing and sharing output from Publisher.
For current versions of Publisher, your best bets for sharing Pub content electronically are printing to the Microsoft Office Document Imaging format (a viewer is part of various versions of Microsoft Office) or saving or printing through one of the various third-party tools that generate PDF.
Somewhat off topic, I also want to call out the Publisher Connect web site, which is a great way to provide us feedback. We recently put up this site and don't have a lot of content there right now, but we do have a way to provide feedback to the product team that won't bottleneck through me. For Publisher support questions, please see the Microsoft Publisher 2003 Help and Support Center on Microsoft Office Online. I cannot provide product support through this blog.