How do current (and traditional) materialists address the problems Kant provided with the separation of noumena and phenomena? It would seem a materialist wishes the phenomena to disappear and leave us with a solid, apodictic understanding of the noumena, for which Kant gives fair arguments against. How would a materialist argue this point, if at all? (If I am misunderstanding the common approach to materialism please provide reference to this as well)
Patricia Churchland, in my opinion, takes materialism to an extreme because of her adherence to eliminativism, i.e. the belief that most people are mistaken about their common-sense understanding of conscious experience. Even so, she has the following to say about Kant's phenomena-noumena distinction:
"Receptors are the interface between world and brain, and our conception of what the universe is like and what we take to be the truth about the universe is inescapably connected to the response characteristics of cells at the periphery. This is what struck Magendie, and later Muller , in their experiments on the specificity of receptors in responding to distinct kinds of physical stimuli. It is probably also the source of the deep currents in Kant's plea for constraints in epistemology - constraints that would acknowledge that our access to the world is always mediated access, access via the nervous system." (Neurophilosophy, p. 43)
Paul and Patricia Churchland, along with others such as Daniel Dennett, try to downplay or deny qualia by passing it off as introspection illusion. Dennett has gone to great lengths in trying to convince people of this:
"Nothing but information passes from outside to inside, and while the receipt of information might provoke the creation of some phenomenological item (to speak as neutrally as possible), it is hard to believe that the information itself — which is just an abstraction made concrete in some modulated physical medium — could be the phenomenological item." (Consciousness Explained, p.55)
I'll have to leave it up to you to interpret the position of the Churchlands and Dennett, because, to me, it appears to be nothing more than an attempt to deny the obvious. Dennett speaks of the same phenomenological experiences as everyone else and then tries to convince people that they are nothing but illusion.
However, speaking of modern philosophers in general, I don't know that anyone really avoids the point that Kant was trying to make. Epistemological idealism is the term often used to refer to the phenomena-noumena distinction, and it seems that it may be the prevalent view in modern philosophy according to the assessment of the Stanford Encyclopedia of Philosophy:
"If epistemological idealism is understood (as has been done here) as involving the claim that what we take to be objects of knowledge are heavily dependent on some activity of the knowing subject, then the very idea of an object as a construction guarantees the endorsement of epistemological idealism. Thus, in contrast to their self-proclaimed revolt against the idealism of Berkeley and Bradley, the positions of both Moore and Russell are by no means free of traits that connect them rather closely to well known currents in modern idealism; and these features, above all the supposition that knowers may be immediately presented with some sorts of informational atoms, whether properties, sense-data, or whatever, but that all further knowledge, or all knowledge beyond immediate acquaintance, involves constructive activities of the mind, are common throughout a great deal of recent philosophy." ("Idealism," Stanford Encyclopedia of Philosophy)