Part of the International Olympic commitment for 2012 is to improve the health and well being of the UK population. One area they have studied is vibration training and I have read their findings in The British Journal of Sports Medicine.
In brief, a group of 12 recreationally healthy volunteers were monitored over 4 week period. Some using vibration plates, some not. The conclusion from the research was vibration training was effective in improving balance, with those using vibration training scoring higher on difficult balance tasks that those that did not.