Here's a news story from The Times about a mobile marketing campaign in the theatre space. Thanks for the lead Adrian. "Theatre companies are sending trailers for their shows to mobile phones around the city in an attempt to attract audiences. Mobile phone users who pass within 100 metres of a portable transmitter set up in the city centre are sent a message asking them if they want to see a trailer. Those who reply "yes" are then sent a clip of the show." 250 people opted in to receive the trailer. My question is this: how many people said "no" when they received the invitation? That would be the telling statistic.