Microsoft has done nothing. Vail is a server OS, based on Windows Server 2008 R2. It will have the same power saving options that that operating system does, but there are no interfaces that expose them in the dashboard. It's possible that some add-in writer
will create an add-in for Vail similar to Lights Out! for Windows Home Server V1. That's probably the best you can hope for regarding hibernation. Wake on LAN has never been "supported" in Windows Home Server either. It requires the right hardware, the right
drivers, and the right configuration to work reliably. Microsoft can't control any of that, so they will leave it up to the end user to implement Wake On LAN if they so desire.
I'm not on the WHS team, I just post a lot. :)