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