Johan has revealed a lot of info about the next major updates on Reddit!
So, we can expect to have rails and minecarts in 0.8.0! He says that as redstone won’t be added till after 0.9.0, powered rails will be automatically forever powered.
Johan also says that redstone will be mineable, just not usable, but it is unclear in what version this will be added.
Here’s a screenshot:
Anyway, here’s the Reddit thread so you can see it yourself.