Coming in to land at Heathrow this evening and I overheard a great conversation on this subject - paraphrased and roghly translated below.

Two PNC asking the head cabin attendant "Do you want to us to have them switch off their tablets?".

The supervisor said "Yes, certainly", one of the PNC then said "But I thought it was OK now", the Supervisor confirmed "No, they should switch them off" and walked away - one of the PNC made a comment to the other along the lines of it really being up to each supervisors feelings.

So, I butted in and said that I had had heard that Ipads were now allowed on take-off/landing. She basically replied "Me Too" (although in a professional and pleasant manner).

Then she went on to explain that although they have been told it is allowed, nobody has seen anything in writing confirming the change, just word of mouth. So until an internal document specifying the change to the policy is issued, it will depend on the inflight supervisor...