While ARM is gaining a lot of momentum, the challenge with ARM until now was that every architecture is very different from different vendors and requires a separate kernel and entire OS stack.
With Linux Kernel 3.7, this has changed for the better.
ARM’s problem was that, unlike the x86 architecture, where one Linux kernel could run on almost any PC or server, almost every ARM system required its own customized Linux kernel. Now with 3.7, ARM architectures can use one single vanilla Linux kernel while keeping their special device sauce in device trees.
The end result is that ARM developers will be able to boot and run Linux on their devices and then worry about getting all the extras to work. This will save them, and the Linux kernel developers, a great deal of time and trouble.
Just as good for those ARM architects and programmers who are working on high-end, 64-bit ARM systems, Linux now supports 64-bit ARM processors. 64-bit ARM CPUs won’t ship until in commercial quantities until 2013. When they do arrive though programmers eager to try 64-bit ARM processors on servers will have Linux ready for them.