Linus Torvalds made the official announcement regarding Kernel 3.4
I just pushed out the 3.4 release. Nothing really exciting happened since -rc7, although the workaround for a linker bug on x86 is larger than I'd have liked at this stage, and sticks out like a sore thumb in the diffstat. That said, it's not like even that patch was really all that scary. In fact, I think the 3.4 release cycle as a whole has been fairly calm. Sure, I always wish for the -rc's to calm down more quickly than they ever seem to do, but I think on the whole we didn't have any big disruptive events, which is just how I like it. Let's hope the 3.5 merge window is a calm one too.
Kernel Newbie has a great listing of new features. The main focus is on CPUs and video cards.
Summary: This release includes several Btrfs updates: support of metadata blocks bigger than 4KB, much improved metadata performance, better error handling and better recovery tools; there is also a new X32 ABI which allows to run programs in 64-bit mode with 32-bit pointers; several updates to the GPU drivers: early modesetting of Nvidia GeForce 600 ‘Kepler’, support of AMD Radeon 7xxx and AMD Trinity APU series, and support of Intel Medfield graphics; there is also support of x86 CPU driver autoprobing, a device-mapper target that stores cryptographic hashes of blocks to check for intrusions, another target to use external read-only devices as origin source of a thin provisioned LVM volume, several perf improvements such as GTK2 report GUI and a new ‘Yama’ security module. There are also many small features and new drivers and fixes are also available.
For those of you wondering, what is a kernel and why should I care? The kernel is the nucleus or controller of the operating system which sits between your computer hardware and software. It is the lowest level of software.