Michel Foucault and Martha Nussbaum covered some similar territory with regard to the ethics of the Ancient world with regard to desire, sexuality, eros and love. In Foucault's case, this was work towards the end of his life in Hermeneutics of the Subject, Uses of Pleasure, and Care of the Self (the last two were volumes two and three of History of Sexuality). In Nussbaum's case, this was the work that really made her name: Fragility of Goodness and Therapy of Desire.
Comparisons of the two are not very frequent. Foucault tends to be best known amongst literary theorists; Nussbaum is known to philosophers (particularly those working in Ancient Philosophy, Philosophy and Literature, and Ethics) and also to people in legal and political theory. There would be great benefits in more philosophers reading Foucault, there would also be benefits in cultural theorists reading Nussbaum.
There are intermittent comments on Foucault in Nussbaum. As far as I know, Foucault never had anything to say about Nussbaum. As far as I know, Nussbaum's major comment on Foucault on antiquity, is that Foucault looked at sexuality with regard to the individual, and paid insufficient regard to the interest in its harmful effects on others in Antiquity. I don't really see a great difference between the fundamentals in how Nussbaum and Foucault present Antique ethics as concerned with the health of the individual.
The underlying difference between the two maybe in what they try to build on Antique ethics. Nussbaum wants to build Aristotelian social democracy, Foucault is concerned with the difficulties of building a theory of political obligation on Aristotle's ethics, or any Antique ethics. For Nussbaum, Aristotle shows a way out of a rigid concern with inner correctness. Aristotle becoems the bearer of an Antique moral externalism (morally significant actions have causes other than inner intentions). Foucault insists on exploring the difficulties Antique ethics poses for generating a sense universality in ethics and politics. The question for Foucault is how a self partly described in sexual terms has the right to sovereignty because it is sovereign over its passions. Upto the Meditations of the Emperor Marcus Aurelius, this poses difficulty for universalising theory. Aurelius does not even think it worth discussing the state directly, it is his daily rule of his passions which settles the question of the legitimation of his power. Foucault explores to the limit, the idea of particular right to sovereignty. This is important to him as it confirms his libertarian tendency to find all power alien. It should also be said that in Hermeneutics of the Subject that Foucault is working on the distinction between pastoral power and governmentality, which is the difference between state absolutism and limited state. So Foucault is beginning to get beyond the gestures towards libertarianism which leave open the question of what the least bad government is in its exercise of power.
Nussbaum is comparatively indifferent to the problems of power in Aristotle, that it rests on a particularistic understanding of who is fit to govern. Despite her discussions of sexuality and a feminine point of view, there is a Puritan desire for morally perfect government with the right to make people good lurking in Nussbaum. This may look harsh but she clearly does not get why Foucault is suspicious of all power and she is advocating a Communitarian type political theory in which the government is moral in purpose. Some of her reactions show a neo-Puritan political correctness completely lacking in Foucault despite his adoption/kidnapping by the politically correct cultural progressives. In Nussbaum's Neo-Puritanism, consider her support for Cartherine McKinnon's proposal to make pornographers open to civil damages because of the supposed consequences of their publications, or her resentment on video that someone commenting on her position on ethical responsibility to animals referred to her 'hunting bigger game' (than Rawlsian political contractualism). I'm concerned about the same issues as Nussbaum is, but I thought that was funny remark and that her response was slightly sinister in its wish to enforce her own very constrained view of civility. She clearly thought the editor should not have allowed such a remark.
Foucault was an irresponsible provocateur, Nussbaum is the New Engşand moralist. Clearly Nussbaum is the greater scholar of Antiquity, by a very long way, but she is not convincing when she tries to criticise Foucault for emphasising the distance between Antique ethics and general theories of obligation. It is important that at this time Foucault was developing a more nuanced view of different types of political regime. In all cases he was trying to learn from Antiquity how politics always refers to particularistic sovereignty.