The pre-release of 1.8 has been "leaked" and you can download it (links below). I say "leaked" with quotes because Jeb has authorised it and is allowing the distribution of it, however it was originally leaked by one of the testing groups. Some people think it's a publicity thing, or they're saying it's "leaked" but it's really so they can treat this as a bug testing stage and everyone is a beta tester. All I know is that you can play 1.8 now, without getting your ass banned from Minecraft.
You can find the official thread for it
here.
You can download the client
here, and the server
here.
Enjoy