I'm running the 1.9 version 2 pre-release on the server. D:
If you would like to play with the new changes it requires downloading this
Then going to wherever your computer keeps the minecraft data, on windows it's found easily by doing a search for %appdata%
from there it's in /roaming/.minecraft/bin and you copy that file you downloaded into that folder. Can make a new folder there called /backups/ or something and then throw your old minecraft.jar into it before you replace it with the new one.http://www.minecraftforum.net/news/245- ... lable-now/
This link is where I got the pre-release, it was given out by Jeb for beta-beta testing purposes while they finalize the stuff they're trying to fit into the official 1.9 release.