If market share data is anything to go by, Apple's iPhone is now being used to access the Internet a third as much as desktop Linux, and it has risen to this level in little more than two years.

Net Applications' "Operating System Market Share" data for August 2009 has the iPhone with 0.33 per cent of the client operating system market, and Linux sitting at 0.94 per cent.

By those numbers, the iPhone is used (to surf the Internet, anyway) by about 35 per cent of the number of people who use Linux on the desktop.

Of course, such statistics need to be put into context.

For starters, the iPhone is competing for Web surfing time with Linux, but it is also competing with every other desktop operating system, including Mac OS X, which according to the same survey is sitting at 4.87 per cent.

Windows remains king at over 93 per cent of Web surfing time. However, the concept of "Web surfing time" can also be misleading.

Operating system market share data is harvested from Web surfing habits and this does not directly equate to the number of installations or users of the operating system.

People may do half (or most) of their Web surfing at work on a Windows PC and use a Mac or Linux at home where the number of hours spent online may be less.

In such cases the raw market share data also shields the preferred operating system from the popular.

Also, as I have discussed in a recent Techworld blog, the rise and fall of market share data can also mask the change in actual installations.

The iPhone’s share has risen at the expense of other operating systems but that does not mean the other operating systems, including Linux, are not still growing.

It just means others are growing faster.

This leads me to another conclusion about OS market share data and mobile Internet use.

Any reasonable comparison of the popularity of an operating system must compare apples with apples -- or in this case mobiles with mobiles and desktops with desktops.

Net Applications’ market share data simply lumps together every operating system in order of “popularity”.

It goes: Windows (all versions), Mac (again, all versions), Linux (all distros), and the iPhone.

From there it’s Java ME (0.31%), Symbian (0.14%), iPod Touch (0.07%) and Windows Mobile (0.04%). Android is behind the PlayStation with 0.02 per cent.