Bernie Thompson, says that all the kernel level code is actually already there in 3.3 and 3.4. So all distros support the hardware at a low level, but there is only higher level support on Fedora 17 right now. It's differences in components at the higher level, that determine whether automatic USB multiseat is supported. Lennart's blog post (and the discussion below it) have good detail.
Currently, higher level support is written into systemd and configured to work out of the box on Fedora 17. It's all open source, so other distros can adopt the feature when ready.
The adapters also function as a laptop docking station for Window machines.