sometimes Cingular and Tmobile leave their very high-end phones unlocked since they know a lot of those buyers will travel. C&W adopted a similar practice here a while back with I believe either Blackberrys or the S/E P series.
either way, the Iphone will work here as long as its unlocked...just be prepared to pay the heavy initial price. $499 & $599 respectively depending on the hard drive size you choose.
p.s. those prices are considering a 2 year contract with Cingular