The new adventure update for that game still doesn't have a release date but we do know that it will not be 1.7 and will be 1.8 as notch is going to make an update with the pistons alone because we wanted it.

He was trying to keep it a surprise but he just couldn't any more though there are still some things that we don't know. What we do know is that it will be a big update. Notch on his blog talked a bit about it and how they will be updating us on the new features while its on its way. Below is a small bit of what we can expect for 1.8.

"Already implemented are new complex terrain features, at least one new mob, some interesting new combat mechanics, a new lighting engine, and some experimental new gameplay ideas. To come is more interesting farming, bigger incentives to explore, and npc villages."