rename is a built-in function. Using it would eliminate the need for File::Copy.

The following is definately untested. Wield at your own risk. ;)

perl -MFile::Find -e "find( sub{ rename( $_, uc $_ ) if -f $_; }, $ARG
+V[0] );" path/name
[download]

Update: Remember, File::Find behaves recursively, unless you explicitly limit it. DO NOT turn this sort of script loose on a root directory, unless you want your entire filestructure to be uppercased.