zRAM has been around for a while now and formerly known as Compcache. The kernel module tries to increase system performance by avoiding paging to disk and instead using a compressed block device in RAM with around a 3:1 compression ratio. Besides Google relying upon zRAM in modern versions of ChromeOS and Android, Ubuntu has also looked at it and other Linux distributions. zRAM is very popular within the embedded space where RAM capacities are limited.
This past August I wrote about zRAM looking to move out of staging in the mainline Linux kernel at the interest of its developers and its stable, widespread usage. However, that didn't happen. With Linux 3.13, zRAM still is not out of staging.
Previously the zRAM promotion was stalled by some other kernel developers wanting zRAM's features to be merged into Zswap, a compressed swap cache for Linux. However, not all developers believe that's a wise idea.
Today another zram/zsmalloc promotion request was sent on the Linux kernel mailing list. We'll see this time if kernel developers decide to move zRAM out of staging for the Linux 3.14 kernel as part of the block driver subsystem.