Linux 3.18-rc2 Brings OverlayFS, Other Late Merges
With the Linux 3.18-rc1 release having been one week sooner than previously expressed, for -rc2 there were some late merge requests, which does include the final landing of OverlayFS in the mainline kernel.
Linus Torvalds isn't too happy about the size of 3.18-rc2 with the post-RC1 merges, but things don't appear to be too incredibly bad and he's just voiced caution about any subsystem maintainers trying to do any more large pull requests this cycle that aren't strictly for bug fixing.
The Linux 3.18-rc2 announcement can be read on the Indiana LKML. Linux 3.18 overall has a ton of new features and improvements as outlined in the features of Linux 3.18.