SATA Express is part of SATA-IO's latest draft, the 3.2 revision
The Serial ATA International Organization (SATA-IO) is always working on something. If it didn't, there would be no advancement on the storage front.Well, maybe there would be some, but they would have to consist of interfaces and technologies other than the poplar SATA specification used by today's HDDs and SSDs.
Anyway, SATA-IO has published the 3.2 revision of the SATA specification.
In it, SATA Express is included. This is a spec that allows SATA and PCI Express storage devices to coexist.
It also brings improvements to power management, optimizations for SSHDs (solid-state hybrid drives) and new SATA form factors.
For those who seek details, The 3.w specification defines microSSDs, Universal Storage Module (USM), DevSleep (the lowest yet level of power management), Transitional Energy Reporting, Hybrid Information, and Rebuild Assist (speeds the data reconstruction process in RAID configurations).