According to answers to questions on superuser and serverfault, OS X Lion had the ability to allow multiple users to simultaneously log in from other Macs and get a VNC session with their own desktop on the target machine (not necessarily running OS X Server, from what I can tell).
For instance, I could connect to our (as yet un-purchased) Mac Mini from a Cafe with my Air, while my wife connects from the living room with her white MacBook, while one of our kids is actually sitting right in front of the Mini using it without screen sharing.
There is no mention of this on Apple's web site, that I can find, but of course they're focused on new features, so that's no surprise. It seems unlikely that they would remove features, but that's not without precedent.
So: can anyone confirm whether or not this feature still exists in OS X Yosemite? (Or Yosemite Server?--although the answers to the other questions did not mention the feature requiring OS X Server.)