The latest version of the mobile that combines a phone with a music and video player was chosen by readers of Britain’s Stuff magazine in its annual Gadget of the Year awards.
The magazine described the iPhone 3G as "a faster, cleverer version of an already remarkable phone". The phone's first incarnation, launched in Britain last year, won the coolest gadget prize at last year's ceremony.
Other nominees included Sony's PlayStation 3, Microsoft's Xbox 360, Nintendo's Wii Fit and the B&W Zeppelin iPod speakers.
Stuff's Editor Fraser Macdonald said the nominated products were judged on their performance, design and value, as well as "that elusive cool factor".
"Having our readers vote for a number of the awards has been fascinating," he said. "They are the ones out there on the street buying gadgets and so they are a great barometer."
The magazine's own gadget of the year prize, chosen by its editorial staff, went to the Asus Eee Pc, a no-frills laptop that costs less than $500.
The judges said it had made more of an impact than any other device and marked the start of a "laptop for everyone" era.
Here are the other main winners, announced at a ceremony at the Dorchester Hotel in London on Tuesday:
International brand: Nokia
Innovation: Sony Reader
Design: Apple MacBook Air
Game: Grand Theft Auto IV
Green gadget: Ego Electric Street Scoota
Retailer: Firebox.com, an online gadget and toy shop