Preview at WWDC likely in June, followed by September launch.
3G iPhone in May, Another Device at WWDC?
As mentioned, SwitchToaMac's source claimed that the 3G-capable iPhone would be announced in May, with the belief that it would be available for purchase the day after the announcement.
The reason for a pre-WWDC announcement? Reportedly, Apple would instead announce a brand new portable device at WWDC. No other details of what this device might be, but there have been rumors that Apple was developing a mini-tablet multitouch device for launch in 2008. This PDA-like device would reportedly have a higher screen resolution (720x480) and be about 1.5x the size of the existing iPhone.
Repubblica.it first reported (in April) that they expected the Italian 3G iPhone launch "in the next few weeks", suggesting a May launch. While Telecom Italia and Vodofone did announce their intentions to supply the iPhone in Italy, no formal announcement had been made from Apple. Meanwhile, Apple's supply of iPhones has dwindled to nothing and our retail sources have indicated that they too will not be receiving many (if any) more iPhone shipments, leading many to speculate that the 3G-capable iPhone launch will be sooner than expected.
We don't necessarily believe this rumor is true, but present it as an interesting possibility. Obviously, we'll see between now and WWDC if it has any merit.