As alexcrichton points out on that bug, it's already implemented:

  rusti> let (a,b,c): (int, uint, float) = std::num::Zero::zero();
  rusti> a
  0
  rusti> b 
  0
  rusti> c
  0

(The explicit type annotations of the tuple are purely because of how rusti works, in most cases they can be dropped as they will be inferred from the use of a, b and c.)