It seems like ketamine might actually have some potential in treatment for depression. BBC News reported on this study in the Journal of Psychopharmacology. It was a very small trial of 28 people with treatment-resistant depression, and ketamine was only effective for 8 of them. Still, if it's reaching any of the people with TRD, that's pretty cool.
Apparently similar trials have been going on for over a decade, with mixed results. There is a lot more research to be done before it can really be explored as a potential treatment, because the side effects are a major consideration, and because the duration of the effect is often very short.
In any case, it seems pretty interesting and it's probably worth keeping an eye on.