In an effort to gain perspective from a variety of sources, I joined a Yahoo group for parents of "late talkers." It's a prolific group with hundreds of members who believe that their children have Einstein Syndrome, rather than autism. And for the record, I believe that many children that talk late DO fall into the category of "late talker" rather than autistic.
The group has a great resource page, with plenty of links to helpful material for late talkers. So far, the group comments have been comprised mostly of exchanging tips ranging from things like preschool to flashcards.
One commenter, however, confirmed what I feared. She posted that her daughter was displaying echolia at 3.5 years, uttering scripts at inappropriate times, clearly a red flag for autism. She wrote that she was crying as she was typing the email. So, the group has a seductive quality for people who aren't ready to accept the truth. My heart goes out to her, as I'm going through that acceptance stage myself.
I'm going to continue to keep my ear to the ground and keep up with the late talker community, with attention to keeping denial in check. I can't go back into denial, and go through this acceptance stage again. But I do want to explore therapies that work for late talkers. Plus, as my pediatrician points out, there is an aspect of self-preservation among the early intervention community. To the extent there is a bias in favor of over-diagnosis, I can only benefit from gaining perspective from outside of the early intervention community.