Re: Time element
There are 2 main use cases for mobile web. One where the user is looking for something in particular, is impatient and does not want distractions. However the second use case is where the user is bored and all they have is their mobile phone to entertain them. It is the second type of user that such adds will be targeting. On old school WAP sites, the click through rate of adverts is actually pretty high, due to the fact that that advert dominates the screen and that the user is only using their mobile phone because they are bored.
Some users will not tolerate adverts of this nature, but I would hazard a guess that the vast majority of users will be happy to receive an interactive advert which distracts them from their otherwise boring life.