I don't know a whole lot about PDD-NOS, but my nephew was diagnose with this when he was 3. He was very behind in his speech and had some of the symptoms of Autism. When he was 7, he had caught up in his speech and his diagnosis was changed to Asperger's Syndrome.
I'm not sure where you're from, but check these sites out
Autism Society of America: Autism Society Canada - Société canadienne de l'autisme