Kristin and All:
We can consider here the example of simulation technologies - these can be very useful, especially of course when it is hard, or dangerous, to replicate the real-world practice of something. There are all sorts of simulation technologies that can really help us learn and master something, such as flight and driving simulators. There are a lot of examples of this used in the military, such as in practicing how to detonate a bomb or the classroom, such as dissecting a frog in science class virtually.
We can apply this as well to other examples cited of social sites that allow users to "practice life" in a general sense (business, relationships, etc.) in something like "Second Life."
Let's continue looking at some of the details of this:
How do we learn from them?
What do we learn from them?
Can they ever completely replace real world training, practice, etc.?