in reply to Perl is psychic?!

according to the Perl5 Pocket Ref, $& is the string matched by the last successful pattern match. Since your regex .* matches anything $& is set to that by the first line, which matches foo and that's what you print in your eval - it eval's $& and finds 'foo' there. I think... =)
"A man's maturity -- consists in having found again the seriousness one had as a child, at play." --Nietzsche