In WSS 2.0 the .pps files we added to document libraries would open in the presentation (slide show) as they do from a file share.  In WSS 3.0 the PowerPoint file always opens like it was a .ppt file rather than a .pps.

Anyone know how to make the slide show run when the file is opened from WSS 3.0.

From what I know, SharePoint will treat the PowerPoint document as a document and not a slide show. 

Here is one way you can get the show to run.

1. Save the PowerPoint document as a web page (.htm or .html file) (Under "Save As" option).
2. Post your new html version of the document into the destination site/list within SharePoint. 
   
3. Click on the document (.html file) to view it in your browser from SharePoint.
   
4. At the bottom right of the page click the "Slide Show" button.
5. In the address bar of your browser, copy the URL (i.e. http://yoursitename.com/documents/slideshow_files/fullscreen.htm#slide0001.htm)
6. You will need to add a Page Viewer Web Part to your site/page.  (Site Actions > Edit Page > Add a Web Part > Page Viewer Web Part)
7. From within the Page Viewer Web Part click the link "open the tool pane"
8. In the Editing Pane (located on the right of the screen in edit mode) paste the URL you copied in step 5.
9. Expand the "Appearance" tab and set your Height and Width as desired.
10. Press Ok.