fun with linux and postfix and dovecot. clues, anyone?

[rmd]

i'm having problems making postfix use dovecot for sasl

so, i'm trying to set up a new centos machine, and want to use dovecot and sasl for authentication. i've been installing everything via yum. postfix looks to have been built with dovecot support built in.

  # postconf -a
  cyrus
  dovecot
  #

and here's the sasl-related part of my postfix main.cf:

  smtpd_sasl_auth_enable = yes
  smtpd_sasl_security_options = noanonymous
  broken_sasl_auth_clients = yes
  smtpd_sasl_type = dovecot
  smtpd_sasl_path = private/auth
  smtpd_sasl_authenticated_header = yes
  smtpd_recipient_restrictions = permit_sasl_authenticated, 
        permit_mynetworks, reject_unauth_destination

my dovecot.conf config has the following set up for auth:

  auth default {
    mechanisms = plain login
    passdb pam {
    }
    userdb passwd {
    }
    user = root
    socket listen {
      client {
        path = /var/spool/postfix/private/auth
        mode = 0660
        user = postfix
        group = postfix
      }
    }
  }

but when i connect to my smtp port, i don't get any kind of "250-AUTH" offering after my EHLO:

  250-PIPELINING
  250-SIZE 10240000
  250-VRFY
  250-ETRN
  250-STARTTLS
  250-ENHANCEDSTATUSCODES
  250-8BITMIME
  250 DSN

what am i missing, here? dovecot and postfix both seem to start cleanly. in rc2.d, dovecot is S65 and postfix is S80, so i don't think postfix is freaking out because it couldn't find dovecot. and restarting either one doesn't seem to matter.