http://www.techpowerup.com/196070/asus-z87-deluxe-sata-express-detailed.html
Two of the motherboard's six SATA 3.0 ports have been replaced with SATA Express. The two data pins in SATA 3.0 will also allow be able to carry data using 2 lanes of PCI Express 2.0 capacity, running for a combined 8Gbps in both directions per lane, for a grand total of 16 Gbps. This should also free up some of the inefficiencies of SATA besides the bandwidth, which so far have been holding plaguing SSD owners.
There are also extra pins within the new SATA ports, which are there to satisfy the requirements of PCIe 3.0, but it's also interesting to note that SATA Express will also be reverse-compatible with existing SATA devices. This means you can still connect a regular SATA 3.0 device to it and it'll work normally, but it will also allow you the full 16 Gbps if you have a SATA Express-supported device. (EDIT: Apparently it uses TWO SATA ports converted into a single SATA Express form factor. It's a very clunky solution from the looks of it, and given all the potential issues with this, I think SATA Express could learn several lessons from DisplayPort connectors. Inside computer cases we normally see short cable runs anyways, so data loss due to long cables shouldn't be too bad. Although I hope optical data cables show up eventually to unlock interference issues and to allow for increased bandwidth.)
I'm curious as to how/if RAID will work. Also, with SATA Express, are we going to see other types of RAID? Also, are we going to see storage devices that have onboard processors (ARM-based probably?) and some RAM, capable of offloading some of the processing to the storage device instead of using up main system resources (and for calculations about internal device optimization - like Samsung 840 EVO SSDs using their proprietary controller, for example, to keep the internal flash from degrading by distributing reads/writes and moving data to increase device longevity).
This could be a big deal. SATA 3.0 limitations no more, hopefully. We've heard about X99 on the Haswell-E side possibly including come of these nifty new ports, as well (bad Haswell pun, maybe?) as DDR4 support. DDR4 modules are still pretty rare, even in the news, and will mostly show up as enterprise parts at first.
As mainstream motherboards requiring DDR4 start to show up (I'm looking at you Intel's forever-QuadCore mainstream line), we might also see the price decrease and the performance increase. With new fabrication processes we'll also densities go up, and both voltage AND heat decrease, allowing for increased clocks once more.
We still have a long ways to go. But this could be a very promising thing for computers. If SATA Express delivers features and performance that justify it in relation to SATA 3.0, and similarly DDR4 vastly improves over DDR3 then the enthusiast will have one more thing to obsess about and one less thing to complain about.
Merry dreaming, enthusiasts whose dreams and ambition outpace their wallets. And for those enthusiasts whose wallet can satisfy the demands of their dreams and ambitions, you have my envy. =P