It could be the 2008 Photokina show in Cologne Germany
or the 2009 PMA (Photo Marketing Association) show in Las Vegas
You might find it at one of the two links (above).
Last year's big camera show (forget the name) was covered by CNET and highlighted an accessory that used some sort of static charge to remove dirt and dust from a camera sensor. I can't remember the name and doing Google searches has been fruitless. Can anyone help out?