From the November 1st issue of New England Journal of Medicine:

Article: "Visualizing Out-of-Body Experiences in the Brain"

Summary - An out-of-body experience was repeatedly elicited during stimulation of the posterior part of the superior temporal gyrus on the right side in a patient in whom electrodes had been implanted to suppress tinnitus. Positron-emission tomographic scanning showed brain activation at the temporoparietal junction — more specifically, at the angular–supramarginal gyrus junction and the superior temporal gyrus–sulcus on the right side. Activation was also noted at the right precuneus and posterior thalamus, extending into the superior vermis. We suggest that activation of these regions is the neural correlate of the disembodiment that is part of the out-of-body experience.

Summary of summary: They caused someone to have an OBE by stimulating a part of the brain with electricity; they think this may be the area where body-consciousness is maintained, and therefore when it is disturbed, a person experiences the feeling of being outside of their body.