http://mobile.emirates.com/english/u...nUpdates.xhtml
Enhanced security measures for flights to USA, Canada and UK
All those travelling to USA, Canada and the UK are required to switch on their electronic devices at the Dubai International airport or risk being denied access to fly. Please ensure that your electronic devices have sufficient power before reaching the airport. This is part of enhanced security measures required by the authorities of these countries.
The USA thing was widely publicized in news etc, but UK and Canada weren't. Thought you all should know.