The rumoured HP iPAQ h6325 with service from Cingular has surfaced on the hp.com site. It is not (yet) available from hpshopping.com but is available from HP in other ways.
Specs-wise, the only difference between it and the h6315 is the carrier and hopefully the fact that it comes with the latest ROM so that issues experienced by T-Mobile users do not repeat themselves at Cingular.
No pricing is available on the web site.