Simple example of what effect a mobile has in flight! Hold it close to a Standby Compass. Now imagine 8 to 350 switched on...with Blackberry's as well!

Not pretty! If you have a heli with SCAS or SAS, and some Numb Nut in the rear decides to attempt sending an email by his Blackberry...
theres a very good chance you'll know when it is transmitting...the Heli will make some uncommanded movements that will rapidly get your attention!
Follow the advice of most Authorities.......Turn the Bloody things off!!