Norman Geras has an interesting post on normblog about whether or not reading literature (and maybe even philosophy) improves our moral character. It's a response to a supposedly knock-down argument against the idea that it does put forward by Stanley Fish. You can read Fish's piece from the New York Times here: 'Will The Humanities Save Us?'
On the question of whether or not reading philosophy improves moral character (a question Norm sidesteps), the answer surely depends on which philosophy you read and in what state of mind. That is, unless you think that it is the act of reading itself that is morally improving. Critical reading, and a concern for consistency, might be thought a stimulus to the kind of reflection that is a pre-requisite of acting morally at all, I suppose...but having the pre-requisite won't guarantee the result (but see earlier post about the UNESCO official line on the value of studying philosophy).