Linux is phasing out support for Intel's i386 architecture, in an effort to simplify maintenance to the operating system's kernel. The changes in the 3.8 version of the kernel marks a departure of the OS from the processor that Linus Torvolds developed Linux on in 1991, an architecture the software supported long after the rest of the computing industry moved on to other architectures.
A Git commit by Ingo Molnar of Red Hat claims that the removal of support for 386-DX/SX processors “zaps quite a bit of complexity” in the kernel, which caused trouble to those working behind the scenes when updating SMP primatives. A "nostalgic cost" was associated with the change, namely the original 386 DX33 system would not “boot modern Linux kernels anymore.” A response back by Torvolds states "I'm not sentimental. Good riddance."
The recently released Linux 3.7, though not mentioning the removal of i386, does add in ARM multi-platform and ARM 64-bit support, a virtual extensible LAN tunnelling protocol, and Intel “supervisor mode access prevention” support.