There is considerable interest in normative ethics regarding whether intentions are relevant for the permissibility of an act, with a number of prominent philosophers such as Judith Jarvis Thomson, Frances Kamm  and Thomas Scanlon  arguing that they are not relevant. See also a nice discussion about this topic at Pea Soup  recently by Alec Walen and Victor Tadros.
Readers of Ethics Etc might be interested in a paper of mine called “Intentions and Moral Permissibility: The Case of Acting Permissibly with Bad Intentions,”  which is forthcoming in Law and Philosophy,  and in which I argue, pace Thomson, Kamm and Scanlon, that intentions can be relevant for the permissibility of an act. A copy of the paper can be found here  and here is an abstract of the paper:
Many people believe in the intention principle, according to which an agent’s intention in performing an act can sometimes make an act that would otherwise have been permissible impermissible, other things being equal. Judith Jarvis Thomson, Frances Kamm and Thomas Scanlon have offered cases that seem to show that it can be permissible for an agent to act even when the agent has bad intentions. If valid, these cases would seem to cast doubt on the intention principle. In this paper, I point out that these cases have confounding factors that have received little attention in the literature. I argue that these confounding factors undermine the putative force of these cases against the intention principle. Indeed, when cases without these confounding factors are considered, it becomes clear, so I argue, that intentions can be relevant for the permissibility of an act.