Steve Jobs, Apple's chief executive, has sweetened the launch of iPhone for employees of his company by promising each a free device.

In a company-wide address to Apple workers Mr Jobs said that each of the firm's 20,000 odd employees would receive a $599 (£299) iPhone for free — a gift with a total retail value of $12 million, according to reports.

As the US geared up for the launch of iPhone at 6pm (New York time) this evening, Apple announced that all its 164 retail stores would stay open until midnight to cater for fans anxious to get their hands on the first devices.

It also unveiled a service on its website which enables customers — who will be limited to 2 iPhones each — to ascertain whether there are devices in stock at their local branch.

Queues of more than 100 people have already formed outside the company's flagship store in Manhattan, with one gentleman — the first to form the line — now in the 4th day of his vigil on 5th Avenue.

Some of the most well-known figures in Silicon Valley including Kevin Rose, the found of the news aggregator site Digg, were in line at Apple's store in Palo Alto.

In New York, there was even an attempted iPhone mugging, when a passer-by made a lunge for one of the devices held by a reviewer for Newsweek magazine - one of four to have been handed out in the country, apparently - as he was being interviewed on live television.

"We've certainly built a lot of iPhones, although it may not be enough," Mr Jobs told the New York Times yesterday, when asked whether supply would meet demand, adding that he was not sure what to expect when 6pm ticked around.

Some observers have suggested that the phone's high price tag — the two models cost $499 and $599 respectively — will mean that initial sales will more likely be in the tens of thousands, rather than millions.

"It's going to be an exciting evening," said Randall Stephenson, chief executive of AT&T — the exclusive carrier of iPhone in the US, which has put on 2,000 extra staff do deal with the rush.

Both men defended the decision to have the phone run on one of AT&T's slower networks, called Edge, saying that the wi-fi connectivity it offered would more than make up for the slower speeds on the cellular network.

In his review of the iPhone in the Wall Street Journal, the respected writer Walt Mossberg said that the relatively sluggish network was the device's "major drawback".

On technology websites, writers could scarcely contain their excitement that the iPhone - one of the most keenly anticipated product launches in memory - was finally becoming available.

"iDay has dawned," read the headline on CNET news, which ran reports that people in the queue in Manhattan had been roundly heckled by passers-by. ("You gonna go on Letterman?," one observer shouted.)

The blog TechCrunch was running a live video stream of the line outside the Palo Alto Apple store, while on Wired.com, under the heading 'Live iPhone Launch Coverage', a report read: "we promise you, as soon as we get our greedy little mitts on one of those buggers, we'll bring you photos, video, reviews, and more."

The online commentary wasn't all so salutary, however. On his blog Robert McLaws said that there was "no point in being on the internet today" because the "mass orgasm" that is the iPhone would be "taking up all of the airwaves", so he was taking the day off instead.

"I'd rather deal with credit bureaus than read one more *$%& thing about the iPhone," he wrote.

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