I see, new for version 3.0. I wonder why they put it there. The example is bad IMHO, because you should know the types you're getting from the database. There goes Microsoft, always wanting to add more features, screwing things up in the process.
I was trying to think of a good use of that in a statically typed language, but everything I thought of had pitfalls and better solutions through inheritance, generics/templates, or other type-safe methods.