Actually, starting with perl5.005, Perl no longer creates a temporary file in /tmp when -e is used. That behavior was a potential security hole, because another process could mess with the file.

Update: I used this in a trivia question at a Mongers party a couple years ago:

Q. Three diagnostic messages are obsolete in perl5.005. All three were related to what Perl feature?

A. The -e command line switch. (All three reported errors with the temp file for -e; in perl5.005 -e no longer creates a temp file.)