Probably the most hyped product of the 21st century so far, Apple’s “revolutionary and magical” iPhone, goes on sale tonight in the United States. Americans have been camping outside stores since Monday to get their hands on the gadget, which has caused feverish excitement among technology devotees.

Priced from $500 (£250), the iPhone will be sold from AT&T and Apple stores from 6pm local time. Apple’s chief executive, Steve Jobs, who has reinvigorated the Californian technology company, claims the iPhone is five years ahead of its time.

He believes it will transform mobile telephony in the same way that the iPod music player transformed the record industry and the Macintosh changed personal computing in the 1980s. About 19 million Americans are expected to buy one, an unprecedented number for a mobile phone.

The iPhone is scheduled to reach Europe later this year, between October and December, once Apple has finalised a tie-up with an as-yet-unnamed telecoms provider to complement AT&T in the US.

Mr Jobs announced the iPhone at the MacWorld show in San Francisco in January. Experts say that Apple’s subsequent slow-burning marketing campaign has created a bigger impact than two other hyped product launches of recent times - Ford’s 1964 Mustang and Microsoft’s Windows 95. In the past six months, there have been 11,000 print articles and 69 million Google hits on the iPhone. The question for consumers is: will the phone live up to its hype?