There is only one solution, namely, a blanket ban on all batteries in checked baggage. This means that people travelling with laptops would not be able to take batteries for them. A benefit of this would be that electronics in the hold could not be left on to communicate with a smartphone in the cabin... surely it is obvious that a bomb-equipped computer in the hold can communicate with a device in the cabin!
I think that a permanent complete ban will quickly lead to improvement of cellphones to act as full-blown computers, with improvement of their operating systems and applications. Airlines could also modify seat back displays to connect with PDA/cellphones, so that the entire phone screen can then be used as a keyboard.
This rather silly ban may act as a stimulus for technological innovation, forcing the "convergence" of smartphone and PC technology, which recently has been dropped or delayed by the likes of Canonical and Microsoft.