well, to determine if a machine could feel pleasure, let's examine why we feel pleasure.

We are programed what is good and bad, some instinct, some learned. (hot stove- instinct, bugs- learned) our brain tells us if what we are interacting with is good or bad, the degree to which we think it is good determines our emotional reaction to it, which was mostly imatation of emotional reactions of our interactions as an infant. (what happens when you smile at a child?)

Sometimes some hormones are released too. well, I suppose a computer can't release hormones. however a computer can be programmed to detect environmental factors that could cause their release and imitate the result of their release in a human being. and a computer can be programmed to learn from interactions with humans, so I suppose that a machine could be programmed to feel pleasure, (or at least act as if it does, which I know isn't feeling pleasure, but hey, that's why it's called "artificial" intelligence)