See also bug #689597. We now set the /Flags in the font descriptor with what we hope is an appropriate value for the symbolic/nonsymbolic flags (which are mutually exclusive). Acrobat can only substitute for missing fonts which are nonsymbolic. Distiller embeds fonts which are symbolic, even if EmbedAllFonts is false. It does this in a complex fashion to do with the re-encoding it always seems to do. We don't need to mimic the re-enmcoding, but we should probably override the EmbedAllFonts setting and embed fonts which are determined to be symbolic.
Enhancement still missing in Ghostscript 9.03
We now mark all TrueType fonts as Symbolic, so this enhancement really doesn't make much sense any more. If we forced the embedding of symbolic fonts we would end up embedding all TrueType fonts.