.html to .shtml

Hey,
I have a website with about 123 pages. I am noticing that more and more webmasters are switching to .shtml format. I can easily change extensions from .html to .shtml by hand since I don’t have very many pages.

What are your thoughts? I am using DreamweaverMX. My site is not database driven so that is why I either have to pick .shtml or .html

Thanks.