The Pre-Release of Minecraft has been released for those who can't wait for the finished product and need something to pass the time, follow the instructions in the link below to use it, I suggest backing up your .minecraft folder if you can, those who regularly install or edit mods for Minecraft will be familiar to this, otherwise it's explained in the link.
http://www.minecraftforum.net/news/214- ... heres-how/