Stereolithography is really neat stuff to work with. We have been using it to a considerable extent on the project I'm currently working on.
Tolerance wise we are holding +/- .005, but it's just like machine work. The closer the tolerance required, the more it costs.
They are also making parts out of scintered (excuse me, I'm an engineer and cannot spell worth crap
) metal, which means depending on their use, do not require any machine work to be used.
We started using the stereolithography process in my area about 12 years ago, so it's been around for a while. Like most things, it's now cheap enough that it's used more.