Quite coincidentally I received an email over the weekend about an upcoming mindfulness training program organised by an Australian MBCT organisation.http://mindfulnesscentre.com/about-us.html
If you have a quick read of the link above, you'd find that the director has trained under some prominent Western insight meditation teachers, including Australian teacher Patrick Kearney, a former monk of the Mahasi tradition who is also a consultant for the organisation and whom some members here hold in high regard.
I don't know about the specifics of MBCT approaches. I do not think that there is anything inherently 'wrong' about such approaches. These approaches can be a means for individuals to engage with 'conventional' reality skillfully. Where it departs from Buddhism, I suppose, is that Buddhism further posits an 'ultimate' reality. However, as I understand it, we are taught that we need to engage with 'conventional' reality skillfully in order to touch 'ultimate' reality. So in this regard, I don't think we can unambiguously dismiss MBCT and other similar approaches as unbeneficial.
But this does not mean that they are beyond critique. Ben makes a good point about the importance of a framework of morality. If such approaches merely appropriate meditation practice for the purpose of strengthening a kind of self-centered individualism, then I think they need to be interrogated on the ethics (or lack thereof) of their actions.