You should put the copying of the files to the webserver in a script (perl, shell, etc.) and execute that script in the cron. It's then pretty trivial to test if the file exists and send a notification if true. A basic shell example would be:
if [ -s newfile.html ]
cp newfile.html /newpath/newfile.html
mail -s "New file for you" firstname.lastname@example.org
If there are multiple files and they can have any name, I would suggest coding the script in perl. That's a bit more complicated, but not hard at all. If you need it, I can post examples of that as well.