Since the 0.5 release affects everyone here, I wrote a longish blog post about what the major changes are: http://julialang.org/blog/2016/10/julia-0.5-highlights.
One other change that I left out of the post because it was getting pretty long and it seems a bit esoteric is that array comprehensions are now type-inference-independent. That means that the type of the resulting array only depends on the actual types of values produced, not what the compiler can prove about the expression in advance. In particular, this means that comprehensions behave the same way in global scope as in local scope now, which is a fairly major relief to anyone who's struggled with that.