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.
Microsoft: Friend or foe?
Tension between Microsoft and the Linux community is certainly nothing new. In 1998, the infamous leaked "Halloween documents" established that, contrary to Microsoft's public statements, the Redmond-based giant considered open source and Linux in particular to be "a significant near-term revenue threat" to Windows.
The Halloween documents further specified various strategies Microsoft could use to attack Linux; most notably, "the effect of patents and copyright in combatting Linux remains to be investigated." Some in the Linux community have dismissed Microsoft's patent claims as mere bluster -- including Linus Torvalds himself. But in 2009, Microsoft sued navigation system vendor TomTom over patents related to Microsoft's FAT32 file system; TomTom eventually settled.
Little wonder, then, that several prominent Linux vendors and customers have opted to preemptively license patents from Microsoft rather than face the possibility of litigation, including Amazon, I-O Data, LG, Linspire, Novell, and Panasonic, among others. Recently, Microsoft signed similar agreements with manufacturers of Android-based smartphones. The net effect is that Microsoft actively profits from Linux businesses even as it works to undermine the popularity of Linux.