Please see So what’s the story with MathType and Microsoft Office 2008? for details. MathType is also compatible with Office 2008 but not all features are available. If MathType is installed, a MathType Equation item appears on the Insert menu in all three iWork applications: Pages, Keynote, and Numbers.
Mac OS X 10.8 Mountain Lion Support: MathType now supports Mac OS X 10.4.9 Tiger or later, including version 10.8 Mountain Lion.