Juan Cole argues that the fatwa's importance has been exaggerated, and that the conclusions of the fatwa are self-evident, namely that if Ahmadinejad stole the election it would be illegitimate for him to occupy the office. This is a very narrow, even strange reading of the fatwa, which clearly, if implicitly, refers to the illegitimate behavior of the rulers, not simply the president. Juan is certainly correct to note the regime has marginalized Montazeri in terms of his access to public space and open discourse in Iran; however, despite the regime's concerted efforts to marginalize Montazeri he retains many middle class followers who consider him to be the most qualified interpreter of religious law. It is instructive to recall that Ali Sistani was marginalized in Saddam Hussein's Iraq, but he retained a wide swath of muqallids or imitators, as the American occupation authorities discovered to their surprise.
I agree that it will take more than a few fatwas from a highly respected mujtahid to move political mountains in Iran, but Montazeri's comments certainly undermine the legitimacy of the President as well as the Leader.