If you're on unix and have the standard find and rename utilities installed, this should work for you. 
% cd YourDocRoot
% find . -name '*.html' -exec rename .html .shtml '{}' \;

[download]
Though you should test it in a temporary directory first.

Update: Here is a faster version using xargs 

% find . -name '*.html' -print0 | xargs -0 rename .html .shtml

[download]

-Blake

In reply to Re: HTML to SHTML to Accomodate SSI's by blakem
in thread HTML to SHTML to Accomodate SSI's by Anonymous Monk

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