Platform support for the A20 and A31 SoCs will be found in the Linux 3.12 kernel. These SoCs aren't some exciting high-end Cortex-A15 SoCs, but rather out of Allwinner -- the name common to powering low-end Android tablets. The A20 is a dual-core Cortex-A7 with Mali-400MP2 graphics and CedarX VPU while the A31 is a quad-core Cortex-A7 with PowerVR SGX544MP2 graphics and a CedarX.
These low-end SoCs have only become a bit more interesting from the Phoronix perspective now that there's been the reverse-engineered video decode acceleration for Allwinner SoCs with CedarX. Right now though that open-source video decode work is targeting the A1x SoCs.
The other ARM-related changes to the Linux 3.12 kernel are scattered about and it's not the most exciting update: there isn't any major AArch64 breakthroughs or any really new hardware support that's super exciting, but just another moderate step forward.
Some of the other work includes DT PCI Express support for NVIDIA's Tegra 4, additional Tegra 4 support enablement, a new "Trats2" Exynos 4 board, preparation of MSI support for Marvell platforms, suspend/PM Tegra updates, OMAP2+ support for the DRA7 Cortex-A15 SoC, and other random code churn.
For those wanting to dig deeper into the ARM changes for Linux 3.12 can look at the SoC merge and boards merge and DeviceTree merge.