If you're inclined to believe financial analysts then mobile device ownership (smartphones + tablets) will trump PC ownership on a global basis some time next year. At some point in the next 3 to 5 years we may have as many or more tablets than PCs. These are radical changes in the marketplace that are still slow to sink in with publishers and advertisers unfortunatley.
The essential thing to understand is that tablets are PC replacement devices in most usage scenarios. Smartphones are used both at home and on the go. They tend to complement PC or laptop usage generally speaking. To accomodate these users and usage scenarios much in advertising, mobile site design and e-commerce has to change.
The following chart from Pew lays out US device ownership and trends over the past six years.
PC ownership (including laptops) has really peaked in the US at about 61% according to the Pew survey data. Mobile phone penetration is 85% (smartphones at 50%+) and tablets at 25% (after the holidays it will be greater).
So what does this all mean in terms of real numbers? It means that if there are roughly 250 million US adults then there are:
If teens are included there are more than 120 million mobile internet users today in the US. That's just over half the total PC internet population.
A new forecast from Informa Telecoms argues that the mobile phone market will be dominated on a global basis by sub-$150 devices by 2017. Regardless of the accuracy of that prediction, prices are indeed coming down. That means more smartphone penetration and more mobile internet access.
What it also means is that PC-centric publishing, e-commerce and advertising will need to give way to a multi-platform approach and a more nuanced and sophisticated understanding of consumer behavior -- amid an even more challenging attribution environment.