WSJ has a Q&A:
The Wall Street Journal Online: How does mobile marketing differ from traditional marketing?
FAREENA SULTAN: The personal nature of the [handheld] device makes it one in which the user is very attached — and at times emotionally attached — to the device. It’s an extension of their personality and of their being, which is particularly true of the youth market. So when a marketer is trying to approach a consumer through this very personal device, they have to be extra careful not to overstep the boundaries. A consumer has asked to be sent information or content or entertainment, so anytime this user receives information that they do not want — it’s bad enough when you are looking at email and getting spam — it’s even worse because it is such a personal device and there’s so much [emotional] attachment to it.
WSJ.COM: So how are advertisers and marketers approaching this situation?
DR. SULTAN: A marketer might think, “Here’s a device, it’s in the hand of my target audience 24-7, and most people are not a foot away from this device 24 hours a day,” so I can reach this person at various locations. A person is in a mall and you send them a solicitation for a coupon for a sale that’s going on nearby. So your ability to reach people is immense and perpetual. But at the same time, you only want to reach the people who want to be reached. If you cross that boundary, the reaction is much worse.