I just came across pharyngula's criticism of Plantinga's short, sweet version of his argument against naturalism. It is here if you are interested.
Plantinga still runs the following type of argument that false beliefs are just as adapative as true beliefs, and so evolution won't particularly favour true-belief-producing mechanisms:
Consider a frog sitting on a lily pad. A fly passes by; the frog flicks out its tongue to capture it. Perhaps the neurophysiology that causes it to do so, also causes beliefs. As far as survival and reproduction is concerned, it won't matter at all what these beliefs are: if that adaptive neurophysiology causes true belief (e.g., those little black things are good to eat), fine. But if it causes false belief (e.g., if I catch the right one, I'll turn into a prince), that's fine too.