tell application "Microsoft PowerPoint"
  tell (slide (my currentSlide())) of active presentation
    return section index
  end tell
end tell

to currentSlide()
  tell application "Microsoft PowerPoint"
    set curSlide to 0
    set theState to (slide state of slide show view of slide show window of active presentation)

    if theState is (slide show state running) or theState is (slide show state paused) then
      set curSlide to (current show position of slide show view of slide show window of active presentation)
    else if (exists active presentation) then
      set curSlide to (slide number of slide range of selection of document window 1)
    end if
    return curSlide
  end tell
end currentSlide