I try to keep things simple: if it's the rule, then obey it - even if the rule makes no sense.

On a recent flight, the guy directly across the aisle from me was typing on his BB during taxi to the runway. FAs were not yet seated and were moving about the aisle. Whenever and FA came close, he would hide the BB in his lap, wait for the FA to pass, and then continue typing. I really don't give a rat's a--, but if you have to sneak it, you certainly are aware it's against the rules and you should put the darn thing away. The world will continue if your BB is off for a while.