Anyone who has studied hypnosis formally won't be particularly surprised by this, but a study has shown that hypnosis can actually allow the brain to suppress memories. From the article:
"MRI scans of their brains under hypnosis showed reduced activity in some brain regions during memory suppression, and increased activity in others.
When their recall was tested later, the suppressed regions were reactivated when the cue was given to bring back the memory."
This is interesting to me not as it relates strictly to hypnosis, but to the power of the mind itself. As I said recently, hypnosis is not a distinct state (i.e. having physiological markers unique to it) but indicative of a particular condition that can occur in many different situations. So, knowing that the mind has the power to suppress memories given a receptive state and a willingness to go along is an important marker.
Imagine if there was a situation where it might be good to be able to get someone to repress the memory of, oh, say, obtaining information from someone... I'm sure you can, can't you?