Hmm... looking at all the recent MacBook Pro model numbers and iMacs, they have all begun with an MC, so unless they are offering a separate model that needs that "D" designation, I don't know - a higher-res option/matte/etc.?
According to Notebook Check, the 6970M is ranked #9, with only two other AMD cards scoring higher (and one is in fact a Crossfire version of it).
When you add in desktop cards, it is ranked #17. Comparatively, through PassMark, it is ranked #13 (which also includes desktop cards). So it certainly looks powerful.
Last year's most powerful iMac card (the Mobility Radeon HD 5850) is ranked down at #91 through PassMark and #61 on Notebook Check.