Of a lot of interest to us (and likely you too) are all of the GPU DRM updates in the Linux 2.6.34 kernel that includes GPU hybrid switching, initial ATI Radeon HD 5000 series KMS support (a.k.a. "Evergreen"), controversial Nouveau changes, ATI Radeon KMS power management support, Intel Sandy Bridge support, and much more.
Outside of the graphics fun in this kernel to be officially released next quarter is a new filesystem (Logfs), a hardware driver for Apple's Magic Mouse, virtualization improvements, and other updates particularly to the Linux drivers and architectures.
The Linux 2.6.34-rc1 kernel release announcement can be read at LKML.org. Over at kernel-tracker.phoromatic.com we continue to benchmark the very latest Linux kernel code on a daily basis on multiple systems. So far there doesn't appear to be any major outstanding performance regressions covered by our tests during the Linux 2.6.34 development thus far.