Interestingly MS-Excel has an export method that can save charts into graphics file-formats. I couldn't see an equivalent while flipping through the PowerPoint object model, but I did come across this code snippet:

Private Sub App_PresentationSave(ByVal Pres As Presentation)
    With Pres.PublishObjects(1)
        PresName = .SlideShowName
        .SourceType = ppPublishAll
        .FileName = "C:\HTMLPres\mallard.htm"
        .HTMLVersion = ppHTMLVersion4
        MsgBox ("Saving presentation " & "'" _
            & PresName & "'" & " in PowerPoint" _
            & Chr(10) & Chr(13) _
            & " format and HTML version 4.0 format")
        .Publish
    End With
End Sub
[download]

This should save a file as both PowerPoint and HTML formats. You could implement this stub in Win32::OLE, if you can put up with the (very) low quality HTML MS-Office emits

Assuming you have access to powerpoint you can also use the File->Save as...-> and then select file type gif, jpg or png and then you can save all slides as gif, jpg or png files. Depending on powerpoint version, I may need to modify your presentation slide sizes so that you get the appropriate image size.

But why bother? You can simply open the PPT up in PowerPoint, and save it as HTML.

Well, one good reason might be that the files are on a machine that doesn't have PowerPoint installed, such as a Unix-based web server that's trying to provide preview thumbnails for files that have been uploaded. (That's why I went looking...)