To clarify a few points, correct some mistakes and give an other point of view...
AoE specs are fully open since day one... :
http://en.wikipedia.org/wiki/ATA_over_Ethernet
Not available on Coraid web site anymore of course but you can find them here (or search on google) :
http://ftp.alyseo.com/pub/partners/Coraid/Docs/AoE/AoEDescription.pdf
Linux driver is also opensource since day one... :
ftp://ftp.alyseo.com/pub/partners/Coraid/Drivers/Linux/
Integrated in LInux kernel for years and now available on github under the OpenAoE community :
https://github.com/OpenAoE/aoe
BSD and Solaris (opensource version) are outdated :
ftp://ftp.alyseo.com/pub/partners/Coraid/Drivers/
But OpenAoE community will work on it...
Some Windows drivers exists and are opensource :
http://winaoe.org/
http://reboot.pro/topic/8168-winvblock/
But guess a vendor will need to take over Coraid on Windows and Vmware driver to ensure certification and support for end users.
Many AoE targets implementation are opensource, make your choice :
vblade[1], a userspace daemon that is part of the aoetools package.
kvblade[2], a Linux kernel module.
ggaoed[3], a userspace daemon that takes advantage of Linux-specific performance features.
qaoed[4], a multithreaded userspace daemon.
aoede[5], a userspace daemon with experimental protocol extensions.
Vblade is under the OpenAoE community and on github now :
https://github.com/OpenAoE/vblade
So you may like or not AoE, but IMHO AoE is not dead and has not died with Coraid...
Let's wait and see, it is just the beginning of the story for OpenAoE and new vendors are coming or reborn with an open approach :
http://www.thebrantleycoilecompany.com/