As per marto's reply, the CPAN is not down. The CPAN is an archive mirrored across almost 500 servers in over 60 countries. It's hard to imagine anything short of the zombie apocalypse taking the CPAN down.
search.cpan.org is down though. search.cpan.org is a sites that provide a nice, searchable interface listing CPAN distributions and showing their documentation. Although it is a popular gateway to the CPAN, it is not the only one.
We also have metacpan.org, which is gaining ground in terms of popularity.
(There was also kobesearch once upon a time, but its maintainer sadly passed away, and the site is no more. There is periodic talk of resurrecting the site.)