I was reading Schwicks ui post on the wow-eu forums today and had a few pictures of the ui from lich king. One of these was a picture of his glyph interface.
As can seen it varies from the standard glyph ui we have seen so far. Instead of 2 greater glyphs, 2 lesser glyphs and two minor glyphs, the interface has three greater and one lesser and two minor.
It seems to me that glyph mastery, rather then provide a seventh glyph for inscribers to use, it upgrades a lesser on to a greater one.
Before you ask, yes Schwich has taken up inscription as a profession. He mentions in his warcraft beta weekly here:http://forums.wow-europe.com/thread....15441553&sid=1