Is there a keyboard shortcut for inserting MathType equations in Pages?
Update for 2019: The newer versions of Pages actually recently added equation support! Just go to Insert > Equation... or hit ⌥⌘E.

It uses LaTeX or MathML, but if you want to use MathType there's apparently a button for that in the resulting dialog, or you can set it to be your default. (I don't have MathType, so I can't test this.)

The Apple Support page has more information.