Should Laptops be Banned in Conferences?

We are at the 4th International Conference on e-Social Science listening to a talk by Alex Voss entitled 'Widening Uptake of e-Infrastructure Services'. The worrying thing is that the majority of the people in the room are using their laptops to check email/surf the web/write blog posts (like us) rather than listen to the presentation.

This poses the questions whether laptops should be banned from such conferences during presentations? It would mean less blog posts but as a presenter myself it can be disheartening to look up only to view a sea of laptops and people typing.

Ok time to stop typing and to listen....