Of all the smartphones sold in the U.S. market, Android now claims the largest share of any OS, and Android is based on the Linux kernel. So are Nokia's Meego and HP/Palm's WebOS -- which, while nowhere near as successful as Android, have hardly fared worse than Windows Phone 7, though the future of WebOS remains in limbo, in light of HP's recent announcement to halt production of WebOS-based devices. In Korea, Samsung's popular Bada OS also uses the Linux kernel, as does the recently announced Aliyun in China.
What that means is that while desktop Linux use may remain low, as consumers forsake PCs for smartphones, Linux gains while desktop operating systems lose -- including Windows.
Linux powers more than just phones, too. The rise of cloud computing and SaaS has spurred demand for new classes of devices that are more lightweight than PCs yet larger and more versatile than smartphones. The market for Android tablets is growing, and they, too, run on Linux. Similarly, Google's Chromebooks, which offer a stripped-down user experience that's little more than a Web browser, rely on the Linux kernel to power their hardware.
Even devices that barely resemble traditional computing platforms are often Linux powered. Leading e-book readers from Amazon, Barnes & Noble, Kobo, and Sony are all based on the open source OS. You'll also find versions of the Linux kernel in networking equipment, GPS navigation systems, media players, TV set-top boxes, and even TVs themselves.
Many of these nontraditional devices are built using inexpensive, low-power processors based on the ARM architecture, which explains why Linux has been so successful in these markets. Robust, full-featured ports of the Linux kernel have been available for ARM since the late 1990s. By comparison, Microsoft's only ARM offering to date has been Windows CE, and it won't have a full-featured OS ready for the architecture until Windows 8 ships in 2012. As a result, Microsoft may remain the biggest threat to Linux's continued growth, even in a post-PC era.