I don't disagree with Wren in that we should provide enough opportunities for our shy ones, but opportunities that are like big bear hugs: comfortable, loving environments.
DD is shy and standoffish. When we were put on a waiting list for preschool at age 2 I enrolled her in a dance class. She stood on the side forever watching the other girls but eventually she joined in and was one of the best in her class. This led to her performance held at a retirement home. I still laugh thinking about that performance. She was deer caught in headlights and didn't perform one bit of her performance, but when the spotlight wasn't on her and she was sitting in the back with her little friends she took over the entire show. She performed everyone else's performances and was jumping up to do the jumps and quickly sitting back down. Then last year she had a proper performance in an auditorium and she did her whole dance with no problems. With this kid we just have to baby step her but she does come out of her shell and surprise us.