I've tried to reproduce the error under perl 5.8.0, but everything works as advertised... I really can't see why it should fail.
You could try to get more info turning debug on with

$smtp = Net::SMTP->new("localhost", Debug=>1)
[download]

and report here what happens... I have no 5.8.2 around, so I just can't try it myself ;-)
In any event, the module source code is pretty compact: it should not be too difficult to debug directly and see where does the error come from.
HTH,
Ant9000