Wow! Minecraft 1.9 Pre-Release already!? Yeah, that's what I thought too. Looks like Notch is pushing for faster updates for the upcoming official release of Minecraft in November. Notch said on his twitter that Minecraft 1.9 will be released after feedback, and 1.10 will have more Adventure Mode content. We should expect to see Minecraft 1.10 Pre-Release being uploaded soon as well.
So what's new in Minecraft 1.9 that's so special anyway? Well there's 3 new mobs, 2 in the Nether and 1 peaceful mob. There's new items in the Nether and in the regular Minecraft world. And there's the new Nether dungeon. A full change list can be found here, as well as the download to the Pre-Release.
You can also watch me talk about the new update below where I show off the new mobs in the Nether and the Nether dungeon: