In recent years, more and more countries report passing the 100% mobile penetration barrier. Currently that is the case in most of the EU member states.
However, it is evident that this figure is not the same as 100% mobile ownership.
There will always be those too young, too old or too disabled to use a mobile phone, some who are too poor or simply elect not to use one. The actual number of mobile phone owners differs from the reported penetration.
On one hand, the definition of an active SIM card differs from country to country.
In Hungary, for example, according to the latest reports the number of SIM cards are able to receive a call, is 114.9 per 100 inhabitants. However the number of those SIM cards from which a call was initiated in the last three months is more than ten percent lower: 102.2%.
On the other hand, owning multiple SIM cards is increasingly common.
For further details on this topic a study from Ewan Sutherland can be found on the following link about the challenge of counting the number of mobile subscribers in context of the reality of multiple SIM card ownership.
http://www.itu.int/ITU-D/ict/statistics/material/sutherland-mobile-numbers.pdf

I think the operators’ marketing plays with over 100% penetration do not help much in getting the right picture. It would be much more helpful to know the percentage of population really using mobile phones (actively/passively) than how many SIM cards were sold.
We lack standards in measuring these figures, in coordinating surveys at least within EU. My experience is we can see several surveys published every year providing incompatible figures and differing a lot, thus bringing only little value in monitoring the markets.
On a related note, I now see the 3G iPhone being advertised on trams here in Budapest. I was in California in July when the model was introduced and the Apple Stores were flooded, with queues down the block.
In the United States at least, Apple has persuaded significant numbers of people to purchase smart phones. ATT originally agreed to pay a cut of subscriber revenues to Apple in exchange for exclusivity because they believed it would bring in new customers. Which is fact it has.
The iPhone already has its imitators and I am sure we will see more. Apple has an early lead but the iPhone is only a part of larger trend, as smart phones become more ubiquitous consumer devices, rather than elitist toys.
As usual, it will take longer than expected for this to happen.
Until then, I suspect the mobile Internet market is mainly about road warriors with laptops. This might be a good to start developing mobile applications and services, but a mass market is still a little over the horizon.