Based on the advice in perlfaq4 (see the section "How can I tell whether a list or array contains a certain element?"), I use a hash for this sort of thing. e.g.:

my %admin_users = (
John => 1,
Bill => 1,
Susie => 1,
);

Then it's easy to test:

if ( $admin_users{$author} )
{
   print $blah;
}
else
{
   print $uber_blah;
}