Earlier this week Gartner released its Q1 handset numbers. What they show is that conventional mobile phones are off almost 9% YoY and smartphones are up almost 13% YoY:

Worldwide mobile phone sales totalled 269.1 million units in the first quarter of 2009, a 8.6 per cent decrease from the first quarter of 2008, according to Gartner, Inc. Smartphone sales surpassed 36.4 million units, a 12.7 per cent increase from the same period last year.

Nokia continues to feel pressure and lose share in a much more competitive environment:

Global handset sales

Smartphone sales

Source: Gartner

If smartphones are 13% - 14% of the market today, we can expect them (depending on pricing) to become 20% - 25% in five or six years. That will mean much more mobile Internet engagment. But it also means that 75%+ of the market will still be on lower-end phones. Lots will happen in the next five years in the mobile market, including the introduction of new tablets, continued growth of netbooks and other IP-connected devices. So it's very difficult to predict mobile user behavior. 

But it's safe to say that most people will not be on these high end devices. Marketers and publishers should be mindful of that.