There is an important but little-known critique of Plantinga's Reformed Epistemology by "star" epistemologist and Christian Keith DeRose (Yale). You can find it here, at DeRose's Yale department webpage.
See also his newer paper on Direct Warrant Realism in the recent phil. of religion collection, God and the Ethics of Belief, edited by Dole and Chignell. It poses problems for Alston's religious epistemology as well. You can read an earlier draft at his department homepage as well, here.