Prior to the Linux Foundation Collaboration Summit in Napa this week was the Linux Storage Filesystem and MM Summit. I wasn't at that event earlier in the week but it was overheard today at the Collaboration Summit that there's talk of encryption support potentially being added to EXT4. Unfortunately I don't have any other information to share at this time about the EXT4 encryption proposal.
Encryption can be done in conjunction with EXT4 right now using eCryptfs or dm-crypt / LUKS; see The Performance Impact Of Linux Disk Encryption On Ubuntu 14.04 LTS for details. Within EXT4 nor any other major Linux file-system is integrated support for transparent encryption. ZFS is one of the major file-systems with such support while EncFS is a FUSE-based encrypted file-system.
When I have any other information on the potential for native EXT4 encryption support I'll pass it along on Phoronix. For those wishing to learn more about Linux disk encryption I would recommend checking out the Arch Linux Wiki.
Talked about also was work on EXT4 and XFS for removing buffer heads from the file-systems. XFS developers are also working on adding persistent memory support to the file-system.