It is here! Minecraft Prerelease 5!
So here is Beta 1.9 pre-release 5: http://assets.minecraft.net/1_9-pre5/minecraft.jar (server is minecraft_server.jar)
Since Jeb mentioned it in a previous posting, it is belived to be a featurefreeze version. This means in the release Version there will be no more new things, just bugfixes compared to the prerelease 5.