Assuming you are using PowerPoint 2003 or earlier, select any slide so that
is it is active -- then choose Format | Slide Layout or similar. This will
open a task pane (or a dialog box in the really old versions). If the layout
being used is the Title Slide, then this slide uses the Title Master -- in
all other cases, it uses the Slide Master.
PowerPoint 2007 doesn't have a separate Title Master -- it uses the concept
of Slide Layouts.